US Government work A work of the United States Government, which US copyright does not cover (17 U.S.C. 105). Record.
231 shots over 27:37, read from the Internet Archive copy gov.archives.arc.37058 (gov.archives.arc.37058_512kb.mp4, 320×240, 29.97 fps). Shot boundaries by PySceneDetect's adaptive detector; each frame links to the Archive's player at that second. Government-works dossier: The story of Hoover Dam US Government work. JSON
Measurements: colour film on its keyframes (231 of 231 shots judged colour), average shot 7.2s long, a frontal face detected in 3% of keyframes. Shots are detected automatically and each is represented by its midpoint frame.
66 beats in 33 sequences, cut automatically at shot boundaries scored on picture change, pauses in speech, topic shifts, on-screen text and cutting rhythm (each beat says why it starts where it does). Each is annotated by a vision-language model from four sampled frames and the transcript lines in it, as observations with evidence; anything the frames and lines do not support is left null. Machine annotation (Qwen/Qwen3-VL-235B-A22B-Instruct), checked automatically: quotes must be verbatim, names must be spoken, "visible" events are sampled to a second model. 66 of 66 beats annotated, 64 passed the checks, 2 flagged.
Passages cut at shot boundaries and annotated by a machine from four sampled frames and the transcript lines in them. Each beat says why it starts where it does and what was checked; sequences are visual groups, not scenes.
0:06Model synopsis: The beat opens with a seal of the U.S. Department of the Interior, and the voiceover introduces Hoover Dam as one of America's seven modern civil engineering wonders. No people are visible or named, and the setting is not established beyond the seal.
“This is the story of Hoover Dam.” 0:08 · “one of America's seven modern civil engineering wonders.” 0:11
0:28Model synopsis: The beat shows a title card for a Bureau of Reclamation film, with voiceover describing a canyon as a modern engineering wonder and previously untouched by man. No people or moving events are visible in the single frame.
“one of America's seven modern civil engineering wonders.” 0:11 · “Build a dam in the wilderness and the world will beat a path to it.” 0:37
Model synopsis: The beat shows a hydroelectric dam in a canyon, with tourists visiting and a yellow boat on a trailer. The narration describes the canyon's transformation from a desolate, sun-scorched place to a site of human engineering and tourism.
1 person observed.
“This was a lonely canyon, unseen and untouched by man.” 0:43 · “Scolded by an angry river slashing its way to the Mother Sea,” 0:50
Model synopsis: A group of tourists is on a guided tour at Hoover Dam, standing on a ramp 560 feet below the dam's top, with a guide speaking about the location. The setting is Black Canyon, at the border of Nevada and Arizona, under bright daylight.
2 people observed.
“Ladies and gentlemen...” 1:26 · “We're now standing on the powerhouse ramp” 1:27
Flagged: time_of_day without evidence (day)
Model synopsis: A group of people observes a dam site while a narrator describes the Colorado River's history and the human effort to control it. Maps illustrate the river's course and the surrounding geography.
3 people observed.
“Here is where man conquered this mighty river.” 1:41 · “placing a concrete yoke about his neck.” 1:44
Model synopsis: The frames show a river in winter with snow-covered banks and turbulent water, followed by a shot of hanging fruit and a windmill in a snowy landscape. The transcript describes historical flooding of the Colorado River, its destructive effects on farmlands and cities, and the subsequent drought that caused suffering for settlers and livestock.
“In 1905, the Colorado cut through its banks below the Mexican border” 2:34 · “and for two years poured unchecked into the Salton sink, forming an inland sea.” 2:40
Model synopsis: The beat shows a dilapidated wooden structure in a dry, hilly landscape with sparse vegetation. The transcript mentions people giving up or staying to fight, and the need to regulate a river.
“Some gave up and went elsewhere.” 3:06 · “Others stayed to fight.” 3:09
3:31Model synopsis: The beat shows a river flowing past rocks, with a voiceover discussing Arthur Powell Davis’s proposal to build a high dam to control floods and droughts, and Congress’s 1928 response. No people are visible; the scene is outdoors with natural lighting.
“No more floods.” 3:18 · “No more droughts.” 3:19
Model synopsis: The beat shows a large assembly hall with many seated people and a speaker at a podium, followed by a close-up of a man signing documents. The transcript mentions Congress passing the Boulder Canyon Project Act in 1928 and President Hoover signing the appropriation bill in 1930.
Named: Herbert Hoover (t:4:04). 3 people observed.
“passed the Boulder Canyon Project Act.” 3:49 · “authorizing construction of Hoover Dam to control and regulate the Colorado River” 3:52
Model synopsis: A group of men are shown on a boat on a river, followed by views of a canyon and a suspension bridge over water. The transcript mentions men, machines, and engineers working on a large dam project.
1 person observed.
“Men and machines went to work to build this dam of unprecedented size.” 4:21 · “this modern,” 4:26
Model synopsis: The segment shows a river in a canyon with water being diverted through tunnels during dam construction. The transcript describes the scale of the tunnels and the effort to divert the Colorado River.
“The thunder of man's determination to conquer the Colorado” 4:43 · “reverberated between the sheer cliffs of Black Canyon as construction got underway.” 4:47
Model synopsis: Workers drill and blast rock in a tunnel, then load debris onto trucks that dump it in a gulch. A truck is shown exiting the tunnel mouth.
3 people observed.
“Drill holes were packed with dynamite and blasted.” 5:08 · “After each explosion, shovels and trucks entered the tunnels” 5:12
Model synopsis: A construction site shows dump trucks unloading rock material near tunnel entrances, with workers present. The transcript states that over 1.5 million cubic yards were excavated in 13 months and the tunnels were lined with three-foot-thick concrete.
2 people observed.
“Workman excavated over one and a half million cubic yards of plaster” 5:20 · “rock material from the four tunnels.” 5:25
5:40Model synopsis: A single frame shows a shadowy figure on a textured surface near a window and a wheel-like object. No people are named, no dialogue is present, and the time of day or period is not established.
5:55Model synopsis: A canyon is shown with explosions and debris, while the transcript describes daily blasts over two years and mentions high scalers preparing canyon walls. No named individuals appear, and the scene is outdoors in daylight.
“Explosions rocked the canyon almost daily for two years.” 5:47 · “before actual placing of concrete in the dam began.” 5:51
Model synopsis: Workers suspended on ropes drill into a rock face and clear debris after explosions. The transcript describes them as 'daredevils' who swarm over cliffs after each blast.
3 people observed.
“Suspended on ropes, they drilled holes in the rock and loaded them with dynamite.” 6:09 · “After each explosion, these daredevils swarmed over the cliffs.” 6:18
6:28Model synopsis: Two figures are climbing a rocky cliff using ropes. The scene is shot in a grainy, low-resolution style with muted colors.
2 people observed.
Model synopsis: A person is shown on a rocky cliff face, followed by aerial views of a river diverted through a canyon and a construction site with smoke, ending with figures near rushing water under a structure. The transcript mentions the Colorado River being diverted under control for the first time in November 1932.
2 people observed.
“Oh, my God.” 6:32 · “In November 1932,” 6:35
Model synopsis: Men and trucks construct earthen coffer dams to divert a river and dry a construction site. Heavy machinery digs 135 feet below the old river level after the area is isolated by the dams.
“Men and trucks dumped an earthen rock embankment across the canyon below the tunnel openings” 6:48 · “A second earth and rock dam was thrown across the river above the tunnel outlets downstream” 7:00
Model synopsis: Heavy machinery excavates rock and earth at a dam construction site, exposing the ancient riverbed. Geologists are mentioned as studying the site's geological history.
“to reach bedrock for the dam's foundation.” 7:21 · “excavating over two million cubic yards of rock” 7:24
Model synopsis: Workmen prepare bedrock for Hoover Dam's foundation while drag lines excavate sand and gravel from an old stream bed on the Arizona side. Heavy machinery, including a suspended bucket, is used in the excavation process.
1 person observed.
“Workmen cleaned and prepared bedrock surfaces to receive the first concrete” 7:40 · “assuring utmost stability for Hoover Dam's foundation.” 7:45
Model synopsis: A train delivers raw material to an aggregate plant where it is processed through screening, grading, and washing before being stockpiled by size. The material is prepared for transport to a dam site.
1 person observed.
“A train hauled this raw material to an aggregate plant across the river, a few miles above the dam site.” 8:03 · “Here the sand and gravel pass through various processes of screening, grading and washing” 8:10
Model synopsis: The segment shows industrial machinery processing aggregate and mixing materials for concrete at a dam construction site, with narration describing the flow to mixing plants and the blending of sand, gravel, and cement. No people are clearly visible or named, and the setting is an outdoor industrial facility with heavy equipment.
“This processed aggregate moved as called for in a steady flow over the railroad” 8:28 · “to two mixing plants” 8:33
8:53Model synopsis: A close-up of a large, rusted industrial machine with visible gears and pipes, shown in a single frame. No people or spoken dialogue are present in this beat.
8:55Model synopsis: A man in white overalls stands beside industrial machinery in a dimly lit interior space. No dialogue or on-screen text is present in this beat.
1 person observed.
8:57Model synopsis: A large industrial machine is shown in an interior setting with a person partially visible beside it. No dialogue or on-screen text is present in this beat.
1 person observed.
Model synopsis: Concrete is dispatched from mixing plants to a canyon construction site via aerial cableways, with the first bucket placed on June 6, 1933. The frames show industrial structures, cableway buckets, and the canyon terrain during this phase of Hoover Dam’s construction.
“From the mixing plants,” 9:01 · “Concrete was dispatched to all points of construction.” 9:02
Model synopsis: Workers are shown at a large-scale dam construction site, pouring concrete into forms as the structure rises. The transcript describes the dam reaching 660 feet thick at its base and being built in five-foot layers.
1 person observed.
“as cableways dumped load after load of concrete into the forms. The dam soon reached its full 660 foot thickness at its base.” 9:29 · “poured in five foot layers of concrete.” 9:39
Model synopsis: A large cylindrical container is transported via cable over a canyon and then emptied into a concrete form at a construction site. Workers are present near the form as the container is lowered and its contents dumped.
2 people observed.
“Bucketful after bucketful ran the continuous cycle.” 9:50 · “Mixing plant to canyon rim, out into mid-air over the gorge,” 9:54
Flagged: name not grounded (null)
Model synopsis: Workers are shown at a construction site handling concrete, with aerial and close-up shots of equipment and labor. The narration states that crews worked continuously through all seasons and conditions, and notes that one year had passed since the first concrete pour by June 1934.
1 person observed.
“The crews vibrated and compacted the fresh pores” 10:08 · “while buckets returned again and again to the mixing plants.” 10:12
Model synopsis: The beat shows construction of Hoover Dam and its associated power plant structures, with frames depicting concrete placement, intake towers, and the U-shaped power plant under construction. The transcript describes the dam's height, its status as a world wonder, and the building of related facilities at the toe of the dam.
“Two-thirds of the dam's concrete had been placed in the forms.” 10:35 · “Already taking its place is one of the world's wonders.” 10:42
Model synopsis: The beat shows construction of tall intake towers for a hydroelectric power plant, built into canyon walls with visible scaffolding and reinforcing steel. The transcript describes their height and placement relative to the dam and canyon rims.
“Intake towers, two on each side, for the power plant's penstock system, climbed as a maze of reinforcing steel and concrete.” 11:04 · “perched on shelves hewn in the canyon walls” 11:14
Model synopsis: The beat shows aerial and ground views of large concrete spillways being constructed against canyon walls, with workers visible on scaffolding. A voiceover explains their function to bypass water and prevent the dam from being overtopped.
1 person observed.
“Two giant spillways were set against the canyon walls on each side of the reservoir just above the dam.” 11:26 · “These high-level controls” 11:32
Model synopsis: The beat shows exterior shots of Hoover Dam's spillway and penstock system, including large pipes and construction activity. A narrator describes the engineering specifications of the dam's components, such as drum gates and steel pipes, and mentions logistical challenges in transporting them.
“plunges downward through the spillway tunnels.” 11:46 · “100 foot long drum gates on the spillway's crests” 11:51
Model synopsis: The beat shows industrial scenes of large steel pipe sections being fabricated and handled at a construction site near a dam, with workers and machinery visible. The transcript explains the pipes were made for the Hoover Dam project and required special equipment.
2 people observed.
“was brought from Eastern Rolling Mills.” 12:25 · “a steel fabrication plant” 12:27
Model synopsis: Workers operate heavy machinery to shape, bend, and roll large metal plates into massive cylindrical pipe sections inside a factory. The transcript explains that three such plates form a ring 30 feet in diameter and 11 feet long.
3 people observed.
“Edges of the dimension plates were shaped on a planing machine to assure precision and accuracy of later steps in their manufacture.” 12:48 · “They were bent on a giant press” 12:57
Model synopsis: A large metal ring is shown being machined on a vertical lathe; the transcript describes joining sections to form penstocks weighing 150 to 184 tons. No people are visible or named, and the location is an industrial workshop.
“two of these rings joined” 13:16 · “weighing 150 to 184 tons.” 13:19
Model synopsis: A large pipe section is transported by a trailer and then moved by a cableway over a gorge. The transcript describes the logistics of moving these sections from a plant to a dam site.
“A train passing through one of the 30-foot sections” 13:35 · “a specially designed trailer, all the sections one at a time down the highway from the plant to the dam site.” 13:47
14:10Model synopsis: A man in a white shirt and cap sits at a table, handling a mechanical device. The setting appears to be an indoor workspace with plain walls and a window.
1 person observed.
14:12Model synopsis: A close-up shot shows a large, dark, circular metal object mounted on a metallic structure. The surrounding surface is textured and appears industrial, with no people or text visible.
14:14Model synopsis: A large industrial machine with exposed gears and wheels is shown in a warehouse-like space. No people or spoken dialogue are visible or audible in this beat.
Model synopsis: Workers are shown inside a large, circular tunnel structure during construction; the transcript describes trailers moving sections into place and joining them with pressure pins to form conduits. No named individuals or specific time of day are visible or mentioned.
3 people observed.
“Trailers waiting at portals of the access tunnels” 14:15 · “carried them to their permanent connections inside the main tunnels.” 14:18
Model synopsis: The beat shows aerial views of a large dam under construction, with concrete being poured and structural elements visible. The transcript states that on May 29, 1935, the last concrete was placed in Hoover Dam, after two years of pouring, totaling over three million cubic yards.
“a continuous stream of concrete had been pouring into the dam for him.” 14:41 · “The structure neared its full height of 726 feet.” 14:46
Model synopsis: The Hoover Dam is shown under construction, followed by a public dedication ceremony where President Franklin Delano Roosevelt speaks. The transcript states the dam was completed ahead of schedule and dedicated on September 30, 1935.
Named: Franklin Delano Roosevelt (t:15:24). 2 people observed.
“this modern civil engineering wonder stood completed” 15:12 · “two and one half years” 15:16
15:45Model synopsis: A single frame shows a large dam structure in a rocky canyon, with water flowing over its crest. The accompanying transcript praises the dam's design and describes it as conquering the Colorado River, with floodwaters lapping against it as the reservoir fills.
“He praised its designers and builders.” 15:30 · “The dam stood like a sentinel” 15:33
Model synopsis: The beat shows interior shots of a large, unfinished turbine pit at Hoover Dam, with a worker standing near its edge. The transcript describes the installation timeline of generators, including the final unit N8, which was installed after a 25-year gap.
1 person observed.
“Turbine pits to hold Hoover Dam's 17 big hydroelectric units were built into the powerhouse.” 16:02 · “The first generator, Unit M2, began commercial operation October 26th” 16:12
Model synopsis: The beat shows workers assembling a massive turbine and butterfly valve inside a power plant, with narration describing the generator's specifications and water control mechanism. No names are spoken, and the setting is industrial machinery within a large hall.
3 people observed.
“It is a 95,000 kilowatt” 17:09 · “60 cycle” 17:12
Model synopsis: A train carrying large industrial parts moves along a curved track near a canyon, and a massive component is suspended by a cableway over the gorge. The transcript describes the delivery of parts to a dam site, noting that such lifts were routine.
“on 60 rail cars.” 17:38 · “Arriving at the canyon rim overlooking the dam, the parts were lifted by cableway and” 17:41
Model synopsis: Two men in hard hats are seen near a large dam structure; one holds a yellow signaling device. A heavy vehicle transports a large component across a bridge in front of the dam. The transcript mentions workers who helped install and operate the cableway during the dam's construction in the early 1930s.
4 people observed.
“and the main cableway operator was the same one who had helped install and operate the cableway” 18:04 · “during the dam's construction in the early 1930s.” 18:10
Model synopsis: A man in light-colored work clothes gestures toward large electrical equipment in a powerhouse. Inside, technicians are shown working with machinery and telephones, and a wide shot reveals massive generators in a long hall.
2 people observed.
“Inside the Nevada wing of the powerhouse,” 18:28 · “technicians assembled and installed the mass of electrical cargo.” 18:31
Model synopsis: Crews prepare a pit for a generating unit by removing slabs and lowering turbine sections into place, which are then bolted and anchored in concrete. Workers are visible in hard hats around heavy machinery and large metal components inside an industrial structure.
2 people observed.
“crews prepared the N8 pit” 18:36 · “They removed temporary slabs over the turbine and relief valve outlets to the tailrace river.” 18:41
Model synopsis: Workers in hard hats assemble large turbine and generator components inside an industrial facility. The transcript describes installing a water wheel, butterfly valve, and stacking steel laminations for rotor and stator parts.
5 people observed.
“Later, the turbine's water wheel” 19:06 · “The butterfly valve was assembled on the generator floor” 19:15
Model synopsis: Workers install a large stator and rotor inside a powerhouse, using overhead cranes to move the heavy components into place over a turbine pit. The rotor is then connected to the turbine water wheel via a large shaft.
3 people observed.
“Coils were locked into place.” 19:34 · “The powerhouse's overhead cranes lifted the completed 254-ton stator” 19:41
Model synopsis: The beat shows large hydroelectric turbines inside a power plant, with workers present during or after installation. The narration states that the Hoover Dam's N8 unit began operation in December 1961, completing the plant's expansion to 1.3 million kilowatts, and that the dam's cost is being repaid via power sales.
4 people observed.
“N8 went on the line December 1st, 1961.” 20:19 · “and to complete the Hoover power plant.” 20:25
21:31Model synopsis: The beat shows Lake Mead behind Hoover Dam, with narration explaining its origin, purpose, and water release for irrigation. No people are visible or named; the focus is on the landscape and the function of the dam.
“The Colorado pours its waters into Lake Mead, named for Dr. Elwood Mead, Reclamation Commissioner during construction.” 21:19 · “Lying calmly behind the dam, these waters await need by downstream users.” 21:29
Model synopsis: The beat shows scenes at Lake Mead, including a dam with traffic, sailboats on water, a car launching a boat, and people swimming. The voiceover describes the lake’s recreational use and benefits for the Pacific Southwest.
1 person observed.
“serve municipal and industrial needs of the Pacific Southwest, generate hydroelectric energy,” 21:44 · “The clear waters of Lake Mead have opened up a vast new recreational” 21:55
22:21Model synopsis: Two people water-ski behind a boat on a large body of water with mountains in the background. The transcript mentions fish, outdoor reclamation products, and Hoover Dam operating around the clock.
2 people observed.
“Fish.” 22:14 · “and enjoy these important outdoor reclamation products.” 22:15
22:39Model synopsis: An animated diagram shows water flowing from Lake Mead through intake towers and penstocks to spin turbines before being discharged into a river. The narration explains this process serves the Pacific Southwest and is repeated at other reclamation dams.
“to serve water and power needs of the Pacific Southwest” 22:30 · “Water from Lake Mead?” 22:34
Model synopsis: The segment shows industrial equipment at Hoover Dam, including transformers and power lines, followed by views of the dam structure and water flowing through its gates. The narration explains the transmission of electricity and water management downstream to Davis Dam and Mexico.
“Transformers step up Hoover Dam voltage, as it comes from the generator.” 22:51 · “Lines carry this power up over the powerhouse roof.” 22:57
Model synopsis: The segment shows infrastructure related to the Colorado River, including a dam structure, transmission towers, and an irrigation canal, while the voiceover describes the interconnected power system and its use for agriculture. No people are visible or named, and the setting is industrial and rural.
“Davis Dam generators interconnect with those at Hoover Dam upstream” 23:32 · “and those at Parker Dam downstream.” 23:36
Model synopsis: The beat shows exterior shots of Parker Dam and associated infrastructure, including power lines and a forebay, while the voiceover describes it as one of America's modern civil engineering wonders and mentions electrical energy from Parker and Hoover power plants. No people are visible or named, and the setting is a desert landscape with mountains and water.
“Parker Dam provides a forebay for the District's Colorado River Aqueduct.” 24:05 · “Another one of America's seven” 24:09
Model synopsis: The segment shows a waterway system, including dams and canals, transporting water from Hoover Dam to agricultural regions in California and Arizona. The narration details the function of Parker Dam, Headgate Rock Dam, Palo Verde Diversion Dam, and Imperial Dam in managing water distribution and flood control.
“pumps water along the aqueduct.” 24:18 · “This waterway delivers municipal and industrial supplies to the Los Angeles and San Diego coastal areas.” 24:21
Model synopsis: The segment shows a large concrete dam structure with water flowing through its gates, identified by the transcript as Imperial Dam on the Colorado River. The narration explains that water from this dam is diverted for irrigation in the U.S. and Mexico, specifically mentioning the Gila Gravity Main Canal and the Alamo Canal.
“The Gila Gravity Main Canal takes water from Imperial Dam” 25:32 · “to valley and mesa lands of the Gila and Yuma Auxiliary Projects.” 25:38
Model synopsis: Two workers are shown tending crops in irrigated fields, with one frame showing a man walking along a water channel and another showing two people working among rows of plants. The transcript mentions food crops grown using water from Hoover Dam and shipped nationwide.
3 people observed.
“into the Alamo Canal.” 25:53 · “grown on lands nourished by water from Hoover Dam.” 26:00
26:53Model synopsis: A man in a hard hat and glasses operates surveying equipment against a rocky backdrop. The voiceover discusses the economic impact of irrigation projects and the expansion of dams along the Colorado River, including Glen Canyon Dam.
1 person observed.
“In return, these irrigated areas buy farm machinery and other products from the manufacturing center.” 26:21 · “Hoover Dam has pointed the way to the fullest utilization of the Colorado River's resources.” 26:45
27:33Model synopsis: A still frame shows the seal of the U.S. Department of the Interior against a blue background. No people, actions, or spoken lines are present in this beat.
Machine transcription of the Archive copy's audio with Whisper large-v3-turbo (temperature 0); the model heard it as en. 409 segments kept, 40 dropped as the kind of hallucination the model produces over music and silence. Each timestamp links to the Archive's player at that second. This has not been checked against the film and can be wrong.
By the average clip vector of the keyframes; a measurement, not a judgement
Unique War 
The General 
War's End