Why do some cities have lots of small multifamiy properties....

[Pat Jackson]

......and others do not? Look at Boise ID. Duplexes (and triplexes and quadplexes) are about as common as hens teeth. Look at Bangor ME. There are tons of small multis. There are a lot of examples like this throughout the country, it’s not just and east and west thing. Thoughts?

[Katie Magoun]

It's pretty simple. Demand = supply. Look to history to see where working-class populations condensed into cities with strong working class industry during industrialization (late 1800s to early 1900s). I can speak to Maine history and say that where you see multis in Maine... mostly in areas with mill work (paper, textile, canneries, etc.). As @Ryan Murdock mentioned, most multi housing stock in Maine is older single families that were long ago converted to multi-family buildings to support the demand for affordable housing near the mill work. I imagine the story is similar in most areas of the country.