KANSAS CITY, Mo. — The National Football League is coming off its best television ratings ever. More people — 111 million — watched last month’s Super Bowl than any program in television history.

But at 11:59 tonight, the world’s most successful professional sports league is expected to come to a grinding halt.

As debate over public employee unions rages in state capitals, the NFL faces its own labor issues: The league’s collective bargaining agreement with the players association expires this evening.

Though the season doesn’t start until September, the league is in jeopardy of losing regular-season games to a work stoppage for the first time since 1987. And such a shutdown would have far-reaching implications in the community.

In Kansas City, each Chiefs game generates an economic impact of about $15 million in the community, according to the Greater Kansas City Sports Commission. And that says nothing of the effect a Chiefs game has on the psyche of the region.

“The fans make the NFL machine what it is,” said Rich Bacchus, a fan from Liberty. “However, we have no union to represent us even though we fund and pay for the entire operation. I have no sympathy for either the players or the owners.”

The major issue on the table is, of course, money, and how to divide $9 billion in revenue among clubs and players.

In the event of a lockout, players would not be allowed to participate in offseason training at practice facilities nor attend offseason practices and minicamps. The league’s nearly 500 free agents couldn’t sign with any teams, and those who have bonus payments due under existing contracts or salary advances against the 2011 season would not receive them.

Though the NFL draft will be held as scheduled April 28-30, teams would not be able to contact their draftees or sign undrafted rookies. Trades could not be made.

From a business standpoint, a lockout would put a crimp on the ability to sell tickets and sponsorships and execute marketing plans. Who’s going to buy a product that does not exist?

New England Patriots owner Robert Kraft told The Boston Globe several weeks ago that if a settlement isn’t reached until Labor Day, or a week before the regular season was scheduled to begin, the ripple effect would be staggering.

“We collectively would lose a billion dollars, even if we played every game but we had this vacuum from the end of the season until the beginning of September,” Kraft said.

If no agreement is reached and a lockout is implemented, the players could decertify the union, a move that would enable them to file an antitrust lawsuit against the owners.

Experts have said the decertification of the union by the players could dissuade the owners from locking out the players, because a lockout under those circumstances could be cited in any antitrust litigation filed by the players.

In the meantime, players will have to work out on their own and hope they have socked away enough money in case the lockout extends into the 2011 season, when they ordinarily would start drawing paychecks.

The NFL bounced back from the 1982 and 1987 work stoppages, but the Patriots’ Kraft is worried about fan backlash.

“For us collectively to mess this up,” Kraft said, “would be criminal.”