ST. LOUIS — Against the strongest field ever assembled for the U.S. Chess Championship, Grandmaster Wesley So of Minnetonka didn't lose a single game — but that wasn't good enough to win the national title.

So finished in second place as his final-round draw left him trailing tournament leader and new U.S. Champion Fabiano Caruana.

So needed a win in Monday's final round and an assist from the last-place, lowest-rated player. He got neither.

He went all in for the win, playing a variation with an immensely imbalanced position that offered risks and rewards for both players, and So was a pawn up. But his opponent defended well and after more than 4½ hours of play and 72 moves, they agreed to a draw.

"Sometimes wild, complicated lines get thrown out there, and in the end, oh, it's a draw," said tournament commentator Maurice Ashley.

"That's the tragedy of chess," said co-commentator Yasser Seirawan.

The game certainly didn't start out that way. Early on, So offered up a rook for capture in order to get his opponent's knight offside and out of the action.

"Wesley wants to win, unlike some people," said Ben Finegold, another commentator, taking a backhanded swipe at Hikaru Nakamura, who opted for a boring and safe draw in his game, despite also having a chance of catching Caruana if he had won and Caruana faltered.

In the end though, it didn't matter, as Caruana beat his opponent, who finished winless at the bottom of the heap, and Caruana secured the championship with 8.5 points. (Players get one point for a win and a half point for a draw.) Even with a win Monday, So couldn't have caught Caruana.

So finished with 7.5 points, with four wins and seven draws. In last year's championship, he had four losses and finished with 6.5 points, so this year was "a clear improvement," So said.

"As a whole, I'm pretty satisfied," he added. "Hopefully, in the next few years I can win this tournament."

With his second-place finish, So earned $35,000. Plus, as one of the top three finishers in the tournament, he qualified for a two-day blitz chess tournament featuring those three qualifiers and former world champion Garry Kasparov, one of the greatest chess players in history. Kasparov, 53, long ago retired from elite competition, but sometimes plays special events like this, and So, 22, has never played him before.

The year ahead promises a steady diet of even tougher competition for So than he faced in St. Louis. In a matter of days he'll fly to Shanghai, China, for a match with Ding Liren, ranked 9th in the world, just one spot ahead of So.

So will also play in the Grand Chess Tour, a series of tournaments in Paris, Brussels, St. Louis and London featuring nine players — all ranked in the top 15 in the world — plus a wildcard entry from each country. The tour carries a total prize fund of more than $1 million.

He'll also try to defend his title at the Bilbao Masters tournament in Spain. And it's a virtual certainty that he'll be playing on the U.S. team at Chess Olympiad in Baku, Azerbaijan, in September. This time, So, Caruana and Nakamura will be playing together as a team, rather than against one another. With all of them ranked among the top 10 in the world, the U.S. has a legitimate shot at the gold medal.

Dennis J. McGrath • 612-673-4293