#Duplexes, #triplexes, and #fourplexes remain a small fraction of overall home #construction despite several states' passage of reforms legalizing this type of "missing middle" housing in all residential #neighborhoods.

https://reason.com/2023/03/14/despite-multiple-states-abolishing-single-family-only-zoning-very-few-duplexes-and-triplexes-are-being-built/