Modern Mechanix

In mid-20th century America–particularly in New York City–a roaring economy emboldened by our ascendant international stature filled many a scholar of public infrastructure with eagerness to execute grand ideas. This proposal to drain the East River to alleviate traffic congestion, for example. Another ambitious but unrealized plan–one that would make it a lot easier to get to New Jersey–was championed in 1934 by one Norman Sper, "noted publicist and engineering scholar," as detailed in Modern Mechanix magazine. In order to address New York City’s traffic and housing problems, Sper proposed that if we were to "plug up the Hudson river at both ends of Manhattan,” and dam and fill the resulting space, the ten square miles gained would provide land to build thousands of additional buildings, as well as to add streets and twice the number of avenues to alleviate an increasingly menacing gridlock.
So how much would it cost?