Also (at least in the Northeast) with the advent of iced-cooled railroad cars in the early 1900's the need to have extensive farmland near cities to feed the population became less crucial. When powered refrigerated cars took off in the early 1950s agriculture almost completely shifted to middle America and all this open land that was once farms became the basis for suburbia. Now instead of spending money to buy a 100 year old row house in a city you could get a plot of land that was once part of a farm for almost nothing and build a new modern house with the latest amenities like a garage, a yard in the back with swingset for the kids, a pool, a deck, a big green lawn, etc.
