We are in West Virginia now, where the only kind of housing that we have come across is -- not surprisingly -- low-density, detached, and single-family. Indeed, approximately 75% of the residential land across the entire US is estimated to be zoned for detached single-family homes. Using data from UrbanFootprint, the NY Times recently published a series of city maps outlining the percentage of land dedicated exclusively to this housing type.

In some cases, such as on residential corner lots in Portland, duplexes are allowed. But generally speaking, the pink corresponds to detached single-family housing. About 15% of residential land in New York City is zoned for this, compared to about 94% of the land in San Jose. Interestingly enough, none of the residential land in Manhattan is zoned to accommodate detached single-family housing.