At a time before the US Soccer team [male and female] became popular in their own country, they played in a few World Cups before 1950. Here are some information taken from the FIFA Classical Football pages for your enjoyment.
1930 FIFA World Cup Uruguay
The US Soccer team participated in the 1930 FIFA World Cup and arrived at the semifinals defeating Belgium and Paraguay. The US eventually lost to Argentina in the semi finals.
1934 FIFA World Cup Italy
The USA lost to Italy in the preliminary rounds.
1950 FIFA World Cup Brazil
The US Soccer team defeated England only to lose to Chile and be eliminated. It would be another 40 years before the US returned to the FIFA World Cup.
Since the 1990's, US Soccer has made great but gradual progress and can boast of greats such as Mia Hamm, Hope Solo, Alex Morgan, Landon Donovan, Carlos Bocanegra, and Jozy Altidore.
The Premier League Insider pays tribute to US Soccer with this historical article.