Some examples of people quickly accomplishing ambitious things together.
Idea from patrickcollison.com.
On July 4, 1861, crews began building the first telegraph line across the continental United States. Working toward each other from east and west, they surveyed routes, dug holes, erected poles, and strung wire at a rate of three to eight miles per day. On October 24, 112 days later, the line was complete, allowing messages to cross the continent almost instantaneously and making the Pony Express obsolete. Source: First transcontinental telegraph.
The Eiffel Tower went up in two years and two months, 793 days, and on completion in 1889 became the tallest structure on earth, a title it held for more than forty years. Source: Eiffel's Tower.
The first subway contract was awarded on February 21, 1900; twenty-eight stations opened and general operation began on October 27, 1904, 4.7 years later. Ninety-six years after that, the MTA decided to build the Second Avenue Subway; its first three stations opened on January 1, 2017. Source: The New York Times.
Donald Hall and Charles Lindbergh took the Spirit of St. Louis from design to finished aircraft in sixty days in 1927. To size the fuel tanks, they drove to the San Diego Public Library and measured New York to Paris on a globe with a piece of string: 3,600 miles, which Hall worked out to 400 gallons of gas. Source: Ryan Airlines gave Lindbergh wings.
Construction of what became the world's tallest building started and finished in 410 days. Source: Empire State Building.
To celebrate finishing its two great bridges, San Francisco built itself a new island: 400 man-made acres in the middle of the Bay for the Golden Gate International Exposition. Work began in 1935 and the island was complete by March 1937. Source: San Francisco Fair: Treasure Island.
The decision to build the world's largest office building was made on a Thursday evening; initial drawings were finished that Sunday. Construction ran from September 11, 1941, to January 15, 1943: 491 days. Asked when anything was needed, its builder Brehon Somervell liked to answer "the day before yesterday." Source: The Pentagon.
Starting in 1942, crews cut 1,700 miles of military roadway through wilderness in 234 days, connecting eastern British Columbia with Fairbanks, Alaska. Source: The Alaska Highway.
The W. A. Bechtel Company received a telegram from the Maritime Commission on March 2, 1942, asking for a new shipyard. The Sausalito site was chosen the next day, the pitch in Washington lasted ten minutes before approval, and construction began within the month, delayed two weeks so the 42 families living on the site could move. The yard's first ship was completed 197 days after the telegram arrived. Source: Marinship on the Fast Track.
On November 16, 1942, Enrico Fermi's team began assembling the world's first nuclear reactor beneath the stands of the University of Chicago's football stadium. They worked around the clock stacking hundreds of tons of graphite and uranium. Fifteen days later the pile was finished. On December 2, it produced the first controlled, self-sustaining nuclear chain reaction in human history. Source: Chicago Pile-1.
In 1943, Tommy Flowers and a small team began developing an electronic machine to attack Germany's Lorenz cipher. Flowers spent eleven months designing and building Colossus, involving roughly 1,500 vacuum tubes at a time when many engineers doubted such a machine could ever operate reliably. By February 1944, it was breaking German messages at Bletchley Park. It became the world's first large-scale programmable electronic digital computer. Source: Colossus.
Kelly Johnson and his Skunk Works team designed, built and delivered the P-80 Shooting Star, the first jet fighter used by the US Air Force, in 143 days. Source: Skunk Works.
Two days after the Soviet Union blockaded Berlin in June 1948, the airlift began: over the following 463 days, the US, the UK and France flew 277,000 flights to supply 2.2 million residents, a plane landing on average every two minutes for 14 months. Tegel airport was built for it along the way; the first landing came 92 days after its construction started. Source: The Candy Bombers.
The United States decided in July 1951 to build the world's first nuclear submarine. It entered service on September 30, 1954, 1,173 days later. Source: Cold War Submarines.
Walt Disney's "Happiest Place on Earth" went from groundbreaking to opening day in 366 days. Source: Under Construction.
In November 1954, the CIA accepted Lockheed's proposal for a radically lightweight aircraft capable of photographing the Soviet Union from previously unreachable altitudes. Kelly Johnson's Skunk Works team produced the new aircraft roughly eight months later. The U-2 made its maiden flight in August 1955 and could operate around 70,000 feet. Source: Lockheed U-2.
Dee Hock was given ninety days to launch the BankAmericard program, the card that grew into Visa, starting from nothing. He made the deadline, signing up more than 100,000 customers along the way. Source: Electronic Value Exchange.
Boeing committed to the 747 program in March 1966. The first completed aircraft rolled out on September 30, 1968, about 930 days later. Source: Boeing 747: A History.
NASA decided on August 9, 1968, that Apollo 8 should go to the Moon. It launched on December 21, 134 days after the decision, and its crew became the first humans to leave Earth orbit. Source: Apollo Spacecraft Chronology.
In 1969, Ken Thompson wrote the first version of Unix in about three weeks on a scavenged PDP-7, roughly a week each for the kernel, the shell, the editor, and the assembler. Source: UNIX: A History and a Memoir.
NASA selected Boeing as prime contractor for the Lunar Roving Vehicle on October 28, 1969. The vehicle had to fold into a tiny compartment of the Lunar Module, survive the lunar environment, work immediately without repairs, and carry two astronauts across the Moon. NASA and Boeing delivered the first flight-ready rover 17 months later. It drove on the Moon during Apollo 15 in July 1971. Source: Lunar Roving Vehicle.
Work on the Alto, the first computer built around a graphical interface, began in November 1972 because Chuck Thacker bet a Xerox executive a case of wine that it could be done "in three months." Hardware, operating system and applications later, the first complete Altos appeared on March 1, 1973. Source: Alan Kay.
In April 1976, the French government approved Europe's first high-speed rail line, Paris to Lyon, including brand-new electric trains to be developed as part of the project. The line opened 1,975 days later, in September 1981. California formed its high-speed rail authority in 1996; the first phase is currently expected around 2033, roughly 13,000 days on. Source: On the Fast Track.
Tim Berners-Lee submitted his first proposal for a distributed information system at CERN in March 1989. By Christmas 1990, he had defined the basic concepts of URLs, HTTP, and HTML and built the first web browser and editor, web server, and website. Roughly 21 months separated the initial proposal from a functioning World Wide Web. Source: CERN / World Wide Web.
Brendan Eich built the first working prototype of JavaScript in ten days in May 1995; it shipped in beta that September. The language now runs on essentially every device with a web browser. Source: Brendan Eich on the history of the language.
Between 1998 and 1999, Shenzhen added a million residents in a single year, growing 22 percent, from 4.4 to 5.4 million people. Source: PopulationStat.
Tony Fadell was hired in late January 2001 to create a music player. Steve Jobs greenlit it in March, a contract manufacturer was hired in April, the product was announced in October, and the first iPods shipped to customers that November, around 290 days after the start. Source: Tony Fadell.
Amazon began building the first version of Prime in late 2004 and announced it on February 2, 2005, about six weeks later, rewiring its delivery promises around a two-day guarantee. Source: The making of Amazon Prime.
Linus Torvalds started writing Git on April 3, 2005, to manage the Linux source code. It was managing its own development four days later, and seventeen days in, a Linux release candidate went out the door tracked by Git. Source: LKML.
The SARS-CoV-2 genome was published on January 10, 2020. Moderna finalized its mRNA vaccine sequence three days later, shipped the first clinical batch to the NIH 45 days in, and on November 16, 311 days after the genome appeared, announced the vaccine was 94.5% effective. Source: Moderna.
Please send me more entries. (Preferably with sources.)