Known broadly as Section 8 , federal financial assistance programs for low-income, disabled and elderly renters were created by Congress in 1974 as an alternative to public housing. Today, the largest such program is the $19 billion-a-year Housing Choice Voucher program, which pays set monthly amounts to help roughly five million people in the U.S. afford market rate rentals. In California, some 300,000 households receive housing choice vouchers, according to the Center on Budget and Policy Priorities Income requirements and voucher limits are set by the U.S. Department of Housing and Urban Development, with participants generally expected to contribute 30 percent of their income. But participants can't simply dig deeper into their pockets to pay for units that cost more than vouchers are worth (currently $925 for a two-bedroom in Stanislaus County). Voucher holders are barred from putting more than 40 percent of their income toward rent and utilities— a restriction meant to make costs sustainable over time, but which becomes problematic if voucher limits don't keep up with the market.As costs rise, thousands on voucher waitlists in the Central Valley have seen the aid program slow to a lurch. Only about 350 people cycle through Stanislaus County's waitlist each year, and many can't get in line. The last public opening for the waitlist was in 2010. Neighboring San Joaquin County, home to cities including Tracy and Stockton, also has a multi-year waitlist.Already, the backlog is having measurable impact. Success rates for securing housing with a voucher have started to decline, from 95 to 87 percent in the last 12-14 months alone, Gonzales said. She attributes the drop primarily to a lack of affordable units, but says the problem is compounded by an influx of low-income residents from expensive markets like the Bay Area seeking to transfer, or " port ," vouchers to the Central Valley."We have some folks from larger metropolitan jurisdictions that sort of waitlist shop," Gonzales said, mentioning outlying areas in the agency's purview, like Alpine County, where "a majority" of those on the waitlist are from the Bay Area.