After a period of slowed growth during the U.S. housing crisis, self-storage has bounced back -- largely because it was already better insulated against economic forces than the housing market.

The subprime mortgage crisis caused a wave of foreclosures, meaning families needed places in which to store their possessions. The $22 billion industry has a remarkably low barrier to entry, with 90 percent of self-storage companies owned by small-business entrepreneurs.

According to the Self Storage Association, there are 2.21 billion square feet of self-storage in this country. That means there are more than 7 square feet of storage per U.S. resident. 

By the numbers:

Percentage of self-storage companies owned by entrepreneurs, according to the Self Storage Association: 90

Expected growth in 2009 revenue for "storage and warehouse leasing," according to IBISWorld: 2.5 percent

Expected annual industry revenue increase growth rate in the four years to 2014, according to IBISWorld: 3.3 percent

Percent of Americans that could stand in U.S. self storage facilities at the same time: 100