It’s the N.F.L.’s most confoundingly persistent record.

On a pleasant Friday evening in the early fall of 1951, Los Angeles Rams quarterback Norm Van Brocklin threw for 554 yards, a single-game record that still stands. The seven-decade-old statistic has been untouchable even in this era of explosive passing offenses and pinball scoring.

Matt Schaub came close in 2012 when he passed for 527 yards for the Houston Texans in a 43-37 overtime win against the Jacksonville Jaguars. Warren Moon of the Houston Oilers also reached that total in a 27-10 win over Kansas City in 1990.

Bengals quarterback Joe Burrow last season threw for 525 yards in a contest Cincinnati won, 41-21, over the Baltimore Ravens. It is the highest single-game total for an active passer.

Even Tom Brady’s biggest career yardage day fell short: In 2011, he passed for 517 yards to lead the New England Patriots over the Miami Dolphins, 38-24. That outing is tied for the ninth-highest single-game total with Jared Goff, who in a 2019 game for the Rams launched as many yards in a 55-44 loss to the Tampa Bay Buccaneers.

“I am amazed that his record still stands,” said Jim Haslett, formerly a defensive coordinator with the Steelers, Saints, Rams and Commanders. “With all the great quarterbacks that have come along, guys like Jim Kelly and Dan Marino, it surprises me that someone by now would not have thrown for 600 yards.”

“I do think the record has a good chance of being broken,” Bill Polian, the former general manager of the Buffalo Bills, Carolina Panthers and Indianapolis Colts, said in an email interview. “What you need is a wild and woolly shootout.”

The circumstances of Van Brocklin’s record-setting stat reveal it as unique beyond the total yardage. For one, Van Brocklin set his record in the “3 yards and a cloud of dust” N.F.L., before the emergence of the rival American Football League in 1960 introduced pro football to wide-open passing offenses and higher-scoring games that captivated audiences.

The 1951 Rams were outliers. Coach Joe Stydahar’s 1950 team still holds the record for most points per game (38.8), which it averaged over a 12-game season, and in 1951, he deployed three-wideout sets in perhaps the first such instance in N.F.L. history, with running back Verda T. Smith, known as Vitamin T., also catching passes.

Van Brocklin had not been scheduled to start the team’s season opener on Sept. 28, 1951. Stydahar planned to juggle between two starters, a practice that had left both Van Brocklin, 25, and the veteran Bob Waterfield, 31, seething. According to reports, Waterfield became ill before the game, and Van Brocklin stepped in.

The Rams played that Friday night in the Los Angeles Memorial Coliseum, where the more popular University of Southern California football team reigned on Saturdays. Their opponent, the New York Yanks, was a ragtag squad comprised mainly of players other teams didn’t want. The Yanks began as the Boston Yanks in 1944. The franchise was folded in 1948 by the owner Ted Collins for tax purposes. Collins moved the team to New York in 1949 as the Bulldogs. The name was changed to Yanks for the 1950 and 1951 seasons.

Perhaps because the Yanks were so inept, Van Brocklin, a Pro Football Hall of Famer known as The Dutchman, had no problem taking the Rams up and down the field. In the first half, he threw touchdown passes of 67 yards to Smith, and a pair of 41- and 47-yard throws to Elroy Hirsch, another member of the Hall of Fame.

“We didn’t rush him at all,” George Taliaferro, who played halfback, quarterback and defensive back for the Yanks that day, told The New York Times in 2011. “We didn’t have that kind of a defense, so he could sit in the pocket and let it go. He didn’t have to scramble.”

Van Brocklin had 27 completions on 41 attempts for five touchdown passes and two interceptions. He completed passes to nine different receivers, led by Hirsch’s nine catches for 173 yards and four touchdowns.

The Rams won easily, 54-14, and went on to victory in that year’s championship game.

Years later, Van Brocklin argued when Sid Gillman was brought in as the Rams’ head coach and demanded a trade, which was completed in 1958, to Philadelphia. There, he led the Eagles to a title in the 1960 season, handing Green Bay Packers Coach Vince Lombardi his only defeat in a championship game.

Van Brocklin retired from playing after that win and in 1961 was named head coach of the expansion Minnesota franchise. As the Vikings’ coach, he constantly feuded with the footloose quarterback Fran Tarkenton since Van Brocklin believed that a quarterback should, as he had, remain in the pocket.

He later coached the Atlanta Falcons, another expansion team. Success eluded him there, too, and he was fired in 1974. Van Brocklin was inducted into the Pro Football Hall of Fame in 1970. He died in 1983 at age 57.

He rarely spoke about the 554-yard performance. “Van Brocklin was often a difficult interview,” said Ray Didinger, who recently retired after 53 years covering Philadelphia sports. “He only wanted to talk about his days in Philadelphia.”