| NFL Teams | 32 franchises (NFL, current) |
| NFL Founded | 1920 |
| MLB Teams | 30 franchises (MLB, current) |
| MLB Founded | 1869 (professional era) |
| NBA Teams | 30 franchises (NBA, current) |
| NBA Founded | 1946 |
| NHL Teams | 32 franchises (NHL, current) |
| NHL Founded | 1917 |
| MLS Teams | 29 franchises (MLS, current) |
| MLS Founded | 1993 |
| Longest Regular Season | MLB (162 games) |
| Shortest Regular Season | NFL (17 games) |
The Big Four: NFL, MLB, NBA, and NHL at a Glance
When fans talk about major American professional sports, they almost always mean the same four leagues. Each has its own rhythm, its own culture, and its own way of crowning a champion. Here's a fast-reference breakdown of the essentials.
| NFL Teams | 32 franchises (NFL, current) |
| NFL Founded | 1920 |
| MLB Teams | 30 franchises (MLB, current) |
| MLB Founded | 1869 (professional era) |
| NBA Teams | 30 franchises (NBA, current) |
| NBA Founded | 1946 |
| NHL Teams | 32 franchises (NHL, current) |
| NHL Founded | 1917 |
| MLS Teams | 29 franchises (MLS, current) |
| MLS Founded | 1993 |
| Longest Regular Season | MLB (162 games) |
| Shortest Regular Season | NFL (17 games) |
The NFL (National Football League) was founded in 1920 and now fields 32 franchises split evenly between the AFC and NFC conferences. Each team plays an 18-week regular season of 17 games, with 14 teams advancing to the playoffs and the season culminating in the Super Bowl — typically the most-watched television event in the U.S. each year.
The MLB (Major League Baseball) traces its roots to 1869 and currently operates 30 teams across the American League and National League. A standard regular season spans 162 games per team, making it the longest grind in the Big Four. Twelve teams qualify for the postseason, which concludes with the World Series. For a deeper look at how MLB's structure evolved over more than a century, see the complete history of MLB's league structure.
The NBA (National Basketball Association), founded in 1946, now features 30 teams in the Eastern and Western Conferences. Each team plays 82 regular-season games, and 16 teams — eight per conference — enter the playoffs, which end with the NBA Finals.
The NHL (National Hockey League) began in 1917 and operates 32 franchises divided into the Eastern and Western Conferences. The regular season runs 82 games, and 16 teams qualify for the Stanley Cup Playoffs.
For a side-by-side comparison of revenue, fan culture, and structure across all four leagues, see how the Big Four stack up.
Season Timing, Playoff Formats, and What Makes Each League Unique
Beyond team counts and founding dates, each league has a distinct seasonal calendar and playoff format that shapes how fans follow the sport.
| League | Season Runs | Regular-Season Games | Playoff Teams | Championship |
|---|---|---|---|---|
| NFL | Sept – Jan | 17 | 14 | Super Bowl |
| MLB | Mar/Apr – Oct | 162 | 12 | World Series |
| NBA | Oct – Jun | 82 | 16 | NBA Finals |
| NHL | Oct – Jun | 82 | 16 | Stanley Cup |
One thing that sets American leagues apart from most global sports is the closed franchise system — no promotion or relegation based on performance. Teams that finish last remain in the same league the following year, though they typically receive higher draft picks as compensation. If terms like conferences, divisions, or wild-card rounds are new to you, this breakdown of how U.S. leagues are organized covers all of it clearly.
It's also worth noting that MLS (Major League Soccer), founded in 1993, has grown to 29 teams and uses a slightly different structure with a playoff format that includes a single-game knockout round — a contrast to the best-of-seven series used by the NBA and NHL. Fans new to any of these leagues can find a broader orientation in this first-timer's guide to U.S. sports.
The dynasties that emerged within these league structures — from the Yankees' World Series runs to the Patriots' Super Bowl dominance — are explored in detail in our look at the most dominant franchises in U.S. sports history.