 Of course, with the difficulties in buying homes, a lot of us continue to rent. A recent report from Rent Cafe, a rental listing website, shows units in the D.C. suburbs are shrinking in size. D.C. ranks number seven on the list of U.S. cities with the smallest average size of new apartments coming in at 744 square feet. According to the report, D.C. apartments have become about 1% larger over the last decade when comparing the average size of units built between 2014 and about two years ago.