1) American Football: 'Football' (American Football) is the most popular sport in America. Ohio league was the first professional football league established in 1903. About 20 years later, name Ohio league was replaced with National Football League(NFL). The highest level competitions in the USA are organized under the NFL. As of 2012, American Football is also the most watched sports on television in country.
2) Baseball: Baseball, also known as United State's "national pastime" is one of the most popular sports in the country. Broadly, competitions are held at two levels - minor league baseball and major league baseball (MLB). These leagues are followed by audience not only in United States, but worldwide.
3) Basketball: Baseball and American Football are closely followed by Basketball in terms of sports popularity in the United States. The NBA (National Basketball Association) competitions, like the MLB and NFL, are followed not only in the United States but throughout the world.
4) Ice Hockey: Ice hockey is the next in the list of most popular sports in USA. Ice hockey originated in the neighbouring country - Canada and soon gained popularity in North America. National Hockey League (NHL), the oldest international Ice Hockey competetion, was founded in Northen America. In 1960, America obtained its first Gold Medal in Winters Olympics. With the introduction of artificial ice rinks, Ice-Hockey has today become a very popular passtime indoor sport.