I’m convinced all major cities have these sorts of crazy plans floating around in their past. Here is one from New York City: dam up the Hudson River so that the land is available for development.

The quest to turn the Hudson into New York’s trendiest new ‘hood, which today no doubt would be stamped with a sexy name like West Chelsea or Watertown, received an amazing five pages of coverage in the March 1934 edition of Modern Mechanix, that non-stop malfunctioning megaphone of bad ideas. Sper seemed earnest in his appraisal of the fill job being within the “abilities of modern engineers,” who were coming off a hot streak of major infrastructure projects…

Critics might cry that the proposal would destroy what remained of the natural beauty of the urban Hudson, ratchet up air pollution and the heat-island effect, and destroy almost half of Manhattan’s beloved and valuable waterfront real estate. But just think of the possibilities of a sixth borough in New York, Sper argued. The mythical land mass would double the number of avenues in Manhattan, relieving daily traffic jams (to those about to point out there would be much more parking and thus more cars, shush). Then there would be the boost to the economy from the construction of electric and commuting infrastructure, as well as the profitable leasing of buildings on 99-year plans, because nothing says desirable location than “sited below a dam.” The subterranean commuters’ labyrinth also would be a “great military defense against gas attack in case of war,” Sper’s reasoning went, “for in it would be room for practically the entire population of the city.”

This was not the first scheme to transform one of New York’s rivers into money-growing terra firma. “I recall some years ago a man named Thompson had a plan to fill in the Harlem River and eliminate the East River entirely,” said one prominent engineer interviewed for the Mechanix piece. And in 2009, Charles Urstadt, the former head of the Battery Park City Authority, suggested doing the same thing by damming the Harlem on both ends to create “thriving neighbors.” As he put it in an editorial in The New York Times: “To ignore today’s opportunities would leave Manhattan lagging behind other forward-looking places like Dubai, Hong Kong, Tokyo and the Netherlands, all of which have reclaimed land from the waters around them.”

In hindsight, this plan seems ridiculous. Yet, it does raise some interesting questions. What if Manhattan wasn’t such a dense island because there was more room to expand? Filling in the river might lead to more economic growth plus more affordable housing. What exactly does New York City do with the Hudson right now anyway? Compared to some other places that have used the waterfront as a means for spurring development as well as creating parks and recreational areas, the Hudson doesn’t quite have the same reputation.

One idea to take away from this is that cities and leaders shouldn’t necessarily fill in land just because they can. At the same time, plenty of important urban land was fill-in. Try to imagine Chicago ending at Michigan Avenue.