A.I. could turn one of our country’s worst habits into a national security crisis.

Detailed accounts of the final hours of the negotiations show that, while the United States offered Canada what it said was the best deal of any country, what Canada had to give up in exchange was seen as unthinkable.

A new study shows that N.F.L. players have a high risk for developing degenerative brain disease. Does anyone in your family play football? We want to know your thoughts.

A new study underscores the danger of playing.

Researchers say it’s all about reducing the total number of blows to the head.

A New York Times/Philadelphia Inquirer/Siena poll found Gov. Josh Shapiro leading Stacy Garrity and having support in the state for a possible presidential bid.

Annie Lowrey, the author of “The Time Tax,” explains how the government steals Americans’ time — on purpose.

President Trump’s endorsement track record is on the line in two races, including the high-profile contest to succeed the late Senator Lindsey Graham.

The administration asked the court to clear the way for President Trump’s order that creates “state citizenship lists” and directs the Postal Service to decide who gets a mail-in ballot.