Better market analysis could solve America's affordable housing crisis, witnesses said Tuesday at Senate hearing. The supply of available low-rent units for people making between $20,000 and $40,000 exceeds demand, but there is a shortage of units cheap enough for the lowest-income Americans, who make less than $20,000 a year, according to Kirk McClure, an urban planning professor at the University of Kansas.

Why it matters: Harvard's Joint Center for Housing Studies predicts the number of Americans who spend half their monthly income on rent will rise 25% to 15 million by 2025. An analysis by the National Low Income Housing Coalition found that there are 35 housing units available for every 100 extremely low-income Americans.

Flashback: Senators Maria Cantwell and Orrin Hatch introduced a bipartisan bill to reform the Low-Income Housing Tax Credit — the nation's largest affordable housing program — in March.