ST. LOUIS — In 1972, Bobby Fischer became the world chess champion in the most-watched chess event in history, a best-of-24-game Cold War match against a Russian grandmaster that routinely jockeyed with the Watergate scandal and the Vietnam War for placement on the evening news. On Monday, Fischer’s most likely American successor, Wesley So, won the United States Chess Championship, cementing his position as the American most likely to win the world title. Only a few dozen people were there to see it.

So’s — and American chess’s — small profile may not last long. The world’s No. 2 player, So is part of a new generation of American chess talents. He changed affiliation from the Philippines team to the U.S. in 2014, the year before Fabiano Caruana, the world No. 4, transferred to the U.S. team from Italy. Rounding out an elite threesome is American stalwart Hikaru Nakamura, world No. 7. The three form the so-called “Holy Trinity” who have transformed a national championship languishing in irrelevance into one of the strongest tournaments on the calendar. They also represent the best chance of an American world champion since Fischer captured the nation’s imagination by single-handedly defeating the Soviet chess machine.

All three were joined by nine other grandmasters in St. Louis over the past two weeks for an 11-game round robin that would decide the title. Caruana and Nakamura had mildly disappointing showings and finished tied for third with a third player. But So lived up to his top billing, tying for first after regulation with the underdog Alexander Onischuk, the 2006 U.S. champion and current world No. 58. So won three games, drawing the rest; Onischuk won four, lost one (to So) and drew the rest.

So’s games showed flashes of brilliance and beauty. On his 21st move of the ninth game, facing 16-year-old world junior champion Jeffery Xiong, So, as black, faced the following position:

So found the best move, according to the computer chess engine Stockfish: sacrificing his knight on the f2 square. It’s far from obvious to a human sitting alone without technological aid, however. Commentators called the gambit “very beautiful,” “sublime” and “unbelievable.” After Xiong captured the knight with his king, So launched a long-range attack, sliding his rook down the length of the board to take the pawn on b2 and putting white in check. After the king retreated to f1, black slid his queen over to h5, setting up a powerful attack from both sides, with the queen on the right and the rook on the left. White could do little to quell the pressure. So went on to win the game 10 moves after the sacrifice. He later said the move was 85 percent calculation, 15 percent intuition.

With a tie between So and Onischuk atop the leaderboard after the 11th round, the tournament headed to rapid overtime games, with each player starting with 25 minutes on his clock, rather than the 90 minutes players had had during regulation. The silence of the tournament, which for two weeks had only occasionally been punctuated by the dull thump of hands hitting chess clocks and throats clearing, became an accelerating crescendo of thwacks as the time wound down. When the final result was decided, after two weeks of play, the pair had mere seconds remaining before instant defeat.

The pressure had an effect. Onischuk cracked on the 20th move of the first tie-breaker game, playing black in the following position:

The best option for black, according to Stockfish, was backing up the queen to b6. Why retreat, leaving the rook at b2 exposed? Even if the rook is left alone, black is later afforded strong counterattacking possibilities: If So, as white, captures the black rook on b2 with his bishop, black can launch its own attack, capturing the knight on e3 with the queen and putting white in check. The white king must then retreat into the corner, and black can capture the pawn on d3 with its bishop, forking white’s queen and rook.

Instead, Onischuk forwent this possible counterattack and retreated his rook to relative safety on b4. After the two traded queens on the d3 square, So pushed his white pawn to f5, forking the black knight and bishop and causing Onischuk all kinds of problems. Onischuk resigned nine moves later.

The current world champion, Magnus Carlsen of Norway, “is the best player in the world,” Maurice Ashley, an American grandmaster and chess commentator, told me. “But Wesley So is playing the best chess in the world.” In a post-tournament interview, So, for his part, described his play over the past two weeks as “so-so.” The next world championship — the championships unfold according to an intricate two-year cycle — is in 2018.

So draws heavily on his Christian faith, and when I asked him whether he was already thinking about a world championship he said, “No.” But he added: “If I ever become a world champion, I will glorify Him in that way.” After the final game, he thanked his parents, U.S. chess benefactor Rex Sinquefield and God. Chess is a lonely pursuit, he explained, and that trinity provides his support.

After the 21st move of the final game, So untucked a necklace with a silver cross from under his sweater. And throughout play, he appeared monklike. “Players think it’s what makes him scary on the board. He doesn’t seem to have anything else going on. He has a lack of distractions,” Robert Hess, an American grandmaster, told me. “I wouldn’t be that surprised if nobody knows Wesley particularly well.”

So’s adoptive mother, Lotis Key, spent most of the final two games in an adjacent room, somewhat removed from the tension. She was reading a book that argues for the role of divine providence in the history of the U.S. Its title: “The American Miracle.”