If housing production is strong and the vacancy rate is stable, why has the city's population not increased? Because household size has been declining rapidly. In fact, Baltimore would have needed to build over 4,000 housing units per year to hold its population steady during the past two years. Fortunately, since average household size rarely drops below two, it will bottom out in just a few years. The current level of housing production, which should continue for at least the next two years, should lead to population growth before 2023.