U.S. airlines and aviation groups are warning Congress that a government shutdown at midnight would disrupt air travel and jeopardize safety.

The federal government officially entered a shutdown at 12:01 a.m. Wednesday amid an impasse on Capitol Hill over competing congressional spending bills.

Since the shutdown began Oct. 1, the Federal Aviation Administration has reported controller shortages in cities across the U.S., from airports in Boston and Philadelphia, to control centers in Atlanta and Houston. Flight delays have spread to airports in Nashville, Dallas, Newark and more.

If a U.S. government shutdown goes on long enough, it could throw a wrench in travel plans, potentially leading to longer airport wait times, flight delays and even cancellations. The shutdown began Wednesday after President Donald Trump and Congress ...