According to National Association of Realtors, the city's vacancy rate is 2.5 percent, a record low.
This means less to choose from. and higher monthly rents. When there are rare vacancies, they don't last long, experts said.
"It's rented even before they're moving out," said Gail Jarvi, manager of 27th East Apartments in Portland.
Adding to the increase in the rental pool has been a drop in home ownership, according to Greg Frick, partner with HFO, Portland's largest apartment investment firm.
Read more at kgw.com.