Another smart post by Old Urbanist analyzing townhouse lots: "Picking up on the topic of block dimensions and street widths from where commenters left off on Monday's post, I thought I'd share what must be the strongest statement ever made on this seemingly pedantic topic, made by architect Ernest Flagg in 1894: 'The greatest evil which ever befell New York City was the division of the blocks into lots of 25 x 100 feet. Fires, pestilence, and financial troubles are as nothing in comparison; for from this division has arisen the New York system of tenement-houses, the worst curse which ever afflicted any great community.' (The New York Tenement-House Evil and Its Cure) "The chronicle of New York's tenement laws from 1879 to 1901 shows an attempt by the city to mitigate the effects of these dimensions, which, it turns out, had been chosen by the city's own hand-picked team of commissioners in 1811 as part of the broader grid plan for New York. In the 1807 state law empowering the commissioners, the New York legislature (at the urging of the city) had set forth certain planning requirements: 1) that no street be less than 50 feet wide, and 2) that once the commissioners had drawn up their plan, no new streets would be opened through city blocks. The reason for these regulations seems to have been in part, according to surveyor John Randel Jr., to '[avoid] confined air, unclean streets, &c.'
"A prohibition on alleys, however, required that all blocks be fairly narrow, since interior block space in wide blocks, without alley access, would be distant from the street and have little economic value. But the commissioners could not go too narrow either: due to the minimum street width requirements, a city with square blocks much less than 200' would have as much as 50 percent of its land area occupied by streets – a poor outcome for commissioners concerned with maximizing the amount of land for sale to private buyers.