The nation is struggling with an affordable-housing crisis. There is not enough housing in communities across the country, including here in Philadelphia. This means families must pay more for their housing, renters have less to get by on at the end of the month, homeownership is out of reach for too many, and those of modest means are forced to live farther from decent jobs.

Homebuilding collapsed during the housing crash more than a decade ago and has been slow to recover. Construction of high-end homes and apartments recovered first, and there is now an oversupply in some urban areas across the country.

However, the construction of affordable housing — homes reasonably priced for lower-income households to rent or own — has only recently begun to increase and continues to lag demand. The shortfall is so large that it would take an extra year of construction at its current pace to close it.

The lion’s share of the undersupply is concentrated in areas that offer significant economic opportunity, driving up house prices and rents for low- and moderate-income families precisely where they want to live.