Anacortes and Skagit County have had very low vacancy rates for a very long time—consistently among the lowest in the state. The chart below shows Anacortes vacancy rates for both rental properties and ownership properties from 2010-2020, as compared to what economists refer to as the "natural" vacancy rates for each property tenure.
Low vacancy means we have a market failure—there aren't enough homes on the market to facilitate the trades necessary for people to buy what they want, even if they can afford it. That means that seniors who may want to downsize, or singles who start a family and need more space, can't sell their homes to move to a better space because there's not enough inventory on the market to support those sales.
As University of Washington Assistant Professor Gregg Colburn explains:
This Strong Towns article has more about vacancy rates.