In America, fall Sundays are for pro football. As are Monday nights, of course.

And now, those who aren’t die-hard football fans — but have a spouse, parents or friends who are — can scratch Thursday night off the social calendar as well. Thursday night NFL football, once a rarity, has gradually become a regular part of the national viewing landscape.

The NFL has always played games on Thanksgiving. And through the early years of the league, a game would be played now and again on nonholiday Thursdays.

But in the 21st century, the occasional Thursday game turned into five per year, then seven. And since last year, the NFL has scheduled a Thursday nighter every week of the season but the last.

Like it or not, the NFL extended weekend is now five days long.

On Oct. 12, 1922, the Rochester Jeffersons lined up against the Akron Pros at Elk’s Field in the newly named National Football League. The game ended in a 13-13 tie when Al Nesser returned a blocked punt for a touchdown. Thursday NFL football was born.

Despite the occasional weekday foray over the next decades, the phenomenon really began in October 1978, when the Vikings visited the Cowboys for the first non-Thanksgiving Thursday game of the Super Bowl era. ABC’s “Monday Night Football” team presided, giving the game a big-event feel. There was complaining about the short rest for the teams, but Vikings coach Bud Grant was sanguine.

“If you’re one of the contending teams, you’ve got to play at odd times,” he told The Chicago Tribune. “Teams like us and Dallas are used to playing at 3 o’clock or on Monday night. It’s the cross you bear.” The Vikings won, 21-10.

In 2002, a Bon Jovi concert led into a game in East Rutherford, New Jersey, and the tradition of a Thursday night season opener began, now generally featuring the defending champion. Jeremy Shockey made his pro debut for the Giants, but they lost to the 49ers, 16-13.

The ubiquity of Thursday night football really began in 2006 when the league added four Thursday games late in the season as a way of boosting the NFL Network, which at the time was on very few cable systems.

The number of weeks with Thursday games continued to increase incrementally, and this season there will be Thursday football in every week but the last, in which every game will fall on Sunday.

Thursday has been an attractive night to the NFL because under the terms of the 1961 law that gave the league its antitrust exemption, it may not play on Friday or Saturday during most of the season to protect high school and college football.

You would not call the Thursday games popular with the teams, exactly. Guard Josh Sitton of the Packers called them “stupid” last year, telling ESPN: “That’s what this league is about, is about making money, which is fine. I like to make money as well. But, yeah, it’s tough on your body, tough on your head.”

Saints coach Sean Payton was incensed last year when his team was asked to play on Thursday after a Sunday night game. “It’s foolish,” he said at a postgame news conference, despite winning. “You got three guys that are hurt in there right now."

Fans and analysts have complained that the players’ short rest makes the games sloppy and unentertaining. But television ratings have been good. Every game on CBS last year was the highest-rated program of the night, and the games on the NFL Network were the highest-rated cable shows of the night. That means that Thursday football is unmistakably here to stay.

Still, Tuesdays and Wednesdays remain pro football free. For now.