A tight housing market has pushed prices out of reach for a large chunk of would-be buyers across the U.S., forcing millions into an apartment market that digs deep into monthly paychecks for rent, especially in high-cost markets like Miami.

Nearly 39 million U.S. residents live in homes they can’t afford, according to a national housing report released Friday by Harvard University. The findings point to a growing concern over housing affordability and shines a glaring light on Miami-Dade County’s pricey market.