It was the day the sponsor of the Kemper Open had been awaiting for three years. When the golf tournament moved here from Charlotte, N.C., the Kemper people were told about the large, enthusiastic galleries that came to the 1964 U.S. Open at Congressional Country Club.

Yesterday, massive traffic jams at noontime--almost two hours before the final threesome of Craig Stadler, Jack Nicklaus and Gil Morgan would tee off--led to the record crowd of 35,000-40,000 that Steve Lesnick, the president of Kemper Sports Management, had expected when he saw the leaders on the scoreboard at the end of Saturday's third round.

Lesnick said that the paid gate for the tournament increased over the first two years. As is the Kemper policy, he would not divulge figures.

"This is the first year we've begun to realize our potential in Washington," Lesnick said. "I'm pleased with the numbers this year. Given the weather, I don't think we could have hoped for a better turnout. Jack Tuthill (PGA Tour tournament director) has always said it takes three years to get established.

"Every hole was lined with spectators for the last five holes. We've never had that here. And I'm not talking just about gate receipts. We feel each tournament has a character to it. And this year the feel of the Kemper Open at Congressional has really come out . . . in the spontaneity at the pro-am dinner, in gallery, in fellowship, in ambiance."

Lesnick would not confirm directly the crowd count offered by one tournament official. He did say: "There were 25-50 percent more people on the course today than Sunday last year."

Some spectators said the traffic delayed them for as long as two hours in getting off the beltway and onto the golf course. Allan Burdette, sergeant of the traffic division of the Montgomery County Police, said, "The crowd (number of cars) today is about three times as big" as last year's final day.

The first two years, Lesnick said, one of his daily chores was sitting in the tournament office on the second floor of the Congressional Country Club clubhouse pondering what attendance figures to announce to the media. "They were guesses," Lesnick said, because there are no turnstiles.

The figures of 30,000 for the 1980 final round and 31,500 for last year's final are felt to be overestimates. Lesnick put it this way, "Whatever you say about attendance, there were more human beings walking the course this year than last year. I'll guarantee that." It rained every day of play except Thursday this year, and a heavy thunderstorm hit a few minutes after play was completed that day. Saturday's round was delayed 2 hours 10 minutes.

Of yesterday's large crowd, Lesnick said, "It was very predictable. We knew it Saturday. The reasons? It was the best job we ever did promoting the tournament prior to the tournament. Ben Brundred (tournament chairman the first two years) spent two years getting this thing well oiled and Bob Miller (the new chairman) has expanded the marketing. There's the (Jack) Nicklaus factor (his first Kemper here). And the poor weather during the week gave some people . . . something like a pent-up demand."

Washington's Lee Elder three-putted two back-nine holes, but still managed an even-par 72 for a 292 total to lead the three local golfers. Fred Funk, University of Maryland assistant, shot 73--296 and Larry Ringer, head pro at the Naval Academy, finished 75--299.

Forty-three golfers, including several who played in the Kemper Open, will play in a 36-hole U.S. Open sectional qualifying round today at the Bethesda Country Club.

Among them will be PGA players Lee Elder, Bob Gilder, David Edwards, Mike Reid, Joe Inman, Dave Stockton and Steve Melnyk. Amateurs will include Gary Marlowe of Woodmont and Jay Sigel, a former British Amateur champion. The 14 low scorers will advance to the U.S. Open at Pebble Beach (Calif.) June 17-20.