Here's what you need to know about who's affected and how it happened.
Who lost benefits?
Anyone who has been collecting unemployment for more than 26 weeks won't be getting anymore checks from the federal government. That's about 1.3 million people at the moment, although several million more people are expected to hit the limit over the course of the next year.
According to the Obama administration, an estimated 4.9 million people will have been affected by the end of 2014.
Why are long-term benefits expiring?
Former President George W. Bush first signed the program into law in 2008, when unemployment stood at 5.6 percent and the average duration of jobless insurance was just over 17 weeks.
The unemployment rate climbed to 10 percent at the height of the Great Recession in 2009, and the government extended the federal benefits for the long-term unemployed for the first time. Since then, they have been extended or expanded 11 times, most recently in January 2013.
Most states have cut back on benefits as the economy has improved.
Republicans signaled they would be open to another expansion of federal benefits if the White House came up with a plan, but one never made it into the bipartisan budget deal passed by Congress last week.
Which states will be impacted the most?
California, Nevada, Illinois, Pennsylvania, Connecticut, New York, New Jersey and Massachusetts, where unemployment rates are still particularly high.
Could an extension still happen?
President Barack Obama has signaled support for a proposal in the Democratic-controlled Senate to extend benefits for three months while a longer-term solution is brokered.
Whether such a proposal stands a chance in the GOP-controlled House remains unclear.