Some examples of people quickly accomplishing ambitious things together.

San Francisco proposed a new bus lane on Van Ness in 2001. Its opening was recently delayed to 2021, yielding a project duration of around 7,300 days. “The project has been delayed due to an increase of wet weather since the project started,” said Paul Rose, a San Francisco Municipal Transportation Agency spokesperson. The project will cost $310 million, i.e. $100,000 per meter. The Alaska Highway, mentioned above, constructed across remote tundra, cost $793 per meter in 2019 dollars.

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What's going on?

The physical infrastructure projects enumerated above occurred before 1970 to a disproportionate degree. Why? Some works containing hypotheses: