The month of March marked the highest number of border-crossing migrants detained by U.S. Customs and Border Patrol since 2006, with more than 171,000 migrants counted, according to data reviewed by The Washington Post.

Compared to January 2021, which saw less than 80,000 migrants, recent weeks have tested the Biden administration’s response to the challenge. The current policy is to detain adult migrants for up to three days and then return them back to Mexico. However, this policy allows some people to keep coming back. Thirty to forty percent of adults that CBP detains have tried to cross at least once before, officials said. The Biden administration is allowing migrants under 18 to stay in the U.S. and seek humanitarian protection.

Additionally, as numbers rise, officials have reported an increasing number of “got aways,” or adults who are seen sneaking away but are not detained, the Washington Post explained. About 1,000 “got aways” are reported every day, which is reportedly the highest number in recent times as the CBP continues to tackle the rising number of migrants attempting to cross into the United States.