In those years, the U.S. Open was played in round-robin preliminary and final sections. However, the next year, Koltanowski returned, not as a player but as the director, introducing the Swiss system to the U.S. Open. He directed the 1947 U.S. Open in Corpus Christi, Texas, using the Swiss system for the first time ever in a U.S. Open chess event. After that, he traversed the country, holding Swiss system tournaments everywhere. Before long, the Swiss system was adopted as the standard for most chess tournaments in America.