WASHINGTON (AP) -- New research finds that college loan debt has stretched to a record number of U.S. households -- nearly 1 in 5 -- with the biggest burdens falling on the young and poor.

Analysis by the Pew Research Center found that 22.4 million households, or 19 percent, had college debt in 2010. That is double the share in 1989, and up from 15 percent in 2007, just prior to the recession. It's the biggest three-year increase in student debt in more than two decades.

The increase was driven by higher tuition costs as well as rising college enrollment during the economic downturn.

Because of the sluggish economy, fewer college students than before are able to settle into full-time careers immediately upon graduation, contributing to a jump in debt among lower-income households. Pew says many of the young adults take on part-time jobs or attend graduate school.