Mexico withdrew its bid in September, leaving the United States as the lone contender from the Americas.
The United States can count on the full support of CONCACAF," CONCACAF president Jack Warner said Monday.
Warner is a member of FIFA's 24-man executive committee, which will decide the 2018 and 2022 hosts in December 2010. Australia, England, Indonesia, Japan, Netherlands-Belgium, Russia, and Spain-Portugal also have bid to host both World Cups, and Qatar and South Korea bid for 2022 only.
England and Spain are viewed as the leading contenders to host in 2018, while the United States is viewed as a top candidate for 2022.
CONCACAF's executive committee decided the United States, Canada and Mexico will play off against the seven Central American nations for five places in the CONCACAF men's youth championships beginning with 2011.
The three North American countries previously received automatic berths for CONCACAF's under-17 and under-20 championships. The Caribbean will keep three teams for each eight-team tournament, held every other year.
There will be a different format for the under-17 tournament in 2011, when Mexico hosts the FIFA tournament and receives an automatic berth.
CONCACAF also ended its participation in the Copa Sudamericana and said it will attempt to keep a presence in the Copa Libertadores, South America's top club tournament.
Panama was given an automatic berth in the first round of next season's CONCACAF Champions League, and El Salvador's two qualifiers will have to start in the preliminary round.