A crumbling college football season took a massive hit Tuesday when the Big Ten and Pac-12, two historic and powerful conferences, succumbed to the pandemic and canceled their fall football seasons.

Five months almost to the day after the first spikes in coronavirus cases in the U.S. led to the cancellation of the NCAA basketball tournaments, the still-raging pandemic is tearing down another American sports institution: fall Saturdays filled with college football.

Despite pleas from players, coaches and President Donald Trump in recent days to play on, 40% of major college football teams have now decided to punt on a fall season, a decision that will cost schools tens of millions of dollars and upends traditions dating back a century.

Both conferences cited the risk of trying to keep players from contracting and spreading the coronavirus when the programs are not operating in a bubble-like the NBA and NHL are doing. They also cited the broader state of the pandemic in the United States, which has had more than 5 million cases of COVID-19.

Two smaller conferences, the Mid-American and Mountain West, had already announced the uncertain move to spring football. The decisions by the deep-pocketed Big Ten and Pac-12, with hundred-million-dollar television contracts and historic programs, shook the foundation of college sports.

The Southeastern Conference and Atlantic Coast Conference released statements expressing cautious optimism. The Big 12 was quiet, but a person familiar with the conference’s discussions told The Associated Press the league was continuing to work toward playing in the fall. The Big 12 has still not released its revised schedule.

The Big Ten said it was postponing all fall sports and hoping to make them up in the second semester. An hour later, the Pac-12, the Big Ten’s Rose Bowl partner, said all sports would be paused until Jan. 1, including basketball.