This post isn't a showcase of interesting buildings or neighborhoods, but an attempt to clarify a small linguistic error that often distorts our view of housing. The word "unit" has become the standard moniker for dwellings in any "big picture" conversation. Unit is an unfortunate and sterile word for the place that people make their lives, but the term has other flaws apart from its lack of intimacy. The word unit has multiple meanings in our language, the most common of which is a consistent quantity of something; as in a unit of measurement. When we talk about housing though we use the word under one of its other definitions, not to mean a specific quantity, but to describe a distinct, individual part. This is an important distinction because a unit of housing is not a quantity of housing. Read that one more time: A unit of housing is not a quantity of housing. A hundred five bedroom houses are not the equivalent of a hundred studio apartments. They are not the same in either the size or in the number of people they are likely to house.
This distinction is obvious when you think about it, but in the flurry of housing statistics that are thrown about it's often lost. Units of housing are easily measured, while considering bedrooms and size to come up with some more accurate estimate of quantity is difficult. But using units as a stand-in for quantity can lead to dramatic distortions. To illustrate the point, Manhattan has far more housing units today than it did in 1900, whole districts full of high-rises have been built, but the residential population is roughly equal. This is largely the consequence of moving from large households of many children, often with extended family members and boarders to small households with disproportionately low numbers of children. On a per person basis, the large households of 1900 were simply a more space efficient living arrangement.
Confusing units for quantity makes small units look like an attractive solution to a housing crisis (on paper) but making units smaller does not necessarily mean housing more people in less space. Sometimes the opposite is true. A family of four could live comfortably in a 1200 sf apartment, but a 300 sf studio pushes the boundaries of human comfort. (Though it is certainly achievable) And consider that in crowded cities, renting a room in a larger house or apartment is generally cheaper than renting a small apartment. There are multiple variables at work here, but most significant is that it simply takes up less space.
Household size is inter-related to the average unit size available in the housing stock. It is not a one-way relationship, but a dynamic one. Where I live in Portland, group houses of 20 and 30 something professionals are common as the city's average unit size is rather large while it has a disproportionate number of young, childless residents. In a context of smaller units many of those group house residents would be inclined to find their own apartment. Similarly where unit sizes are relatively large families are likely to take in relatives or boarders while smaller units will likely see more strictly nuclear families. We don't get to rebuild the city from the ground up every generation, one way or another the people make a way to square their preferences with the stock of housing they inherit. All of this is to say that when we talk about a shortage of housing we need to make some sophisticated judgements about housing quantity rather than just resorting to the simple but flawed method of counting units.