Throughout its history, Major League Baseball has featured numerous rivalries between teams and cities. These rivalries have developed for a variety of reasons, most commonly geographic proximity, frequent competition, specific incidents, cultural, linguistic, national affiliations, and division rivalry.

Background

There were 8 teams in each league and teams in each league played each other 22 times a season. With the second American League incarnation of the Washington Senators (now the Texas Rangers) and the Los Angeles Angels entering play as expansion teams in , MLB increased the total number of games American League teams played to 162, which meant teams would play each other 18 times a season. The National League did not implement this until the following year when the New York Mets and Houston Colt .45s (now the Houston Astros) entered play.

In , with the San Diego Padres, Seattle Pilots, Kansas City Royals, and Montreal Expos entering play as expansion teams, MLB split both leagues into two divisions with six teams each. Teams played a total of 90 intra-divisional games, playing teams within the division 18 times each, and 72 inter-divisional games, playing each team in the other division 12 times. However, in , the addition of the Seattle Mariners and Toronto Blue Jays reduced the number of intra-divisional games American League teams played to 78, as each team would play each team within the division 13 times. However, they still played each team in the other division 12 times, but the total number of inter-divisional games increased to 84. The National League did not institute this until , when the Florida Marlins and Colorado Rockies entered play.

In , MLB split each league into three divisions, but kept the 1993 format in scheduling. In , with MLB adopting interleague play, the schedules were changed. The schedule for interleague play comprised 84 three-game series, namely six series (eighteen games) for each of fourteen AL teams and as many as six for each of sixteen NL teams.

MLB changed its scheduling format in , further intensifying division matchups throughout the league. The new "unbalanced schedule" allowed for additional games in each season between divisional rivals, replacing additional series with teams outside the division. Due to the change, division rivals now played each other 17 or more times each season. The scheduling drew criticism both when it was enacted and after the fact, with some analysts even positing that the unbalanced schedule hurt intra-divisional play.

With the Astros moving to the American League West in , MLB changed its scheduling formula as a result of each division having five teams. Teams play a total of 76 intra-divisional games, playing teams within the division 19 times each, and six or seven games against other teams in their leagues and 20 interleague games. The move of the Astros led to interleague play throughout the season. The number of interleague games against natural rivals was reduced from six to four. Beginning in 2023, intradivisional games were reduced to 13 while teams get three interleague games against each non-natural opponent and four against a natural rival.

In 2025, a new "MLB Rivalry Weekend" was revealed, with the first edition taking place in the third weekend of May. During this weekend, nearly every team plays a designated interleague rival. 11 of the 15 Rivalry Weekend matchups are interleague, with three being intradivision and one being intraleague.

American League

American League East

Boston Red Sox vs. New York Yankees

The Yankees–Red Sox rivalry is one of the oldest, most famous, and fiercest rivalries in American sports. For more than 120 years, the Boston Red Sox and New York Yankees have been intense rivals.

The rivalry is often a heated subject of conversation in the Northeastern United States. Since the inception of the wild card team and an added Division Series, the AL East rivals have squared off in the American League Championship Series three times: The Yankees won in 1999 and 2003, and the Red Sox won in 2004. The two also faced off in the American League Division Series in 2018, with the Red Sox winning in four games. The teams most recently played in the 2025 American League Wild Card Series, which the Yankees won at Yankee Stadium. In addition, the teams have twice met in the last regular-season series of a season to decide the league title, in (when the Red Sox won) and (when the Yankees won).

The teams also finished tied for first in , when the Yankees won a high-profile one-game playoff for the division title. The 1978 division race is memorable for the Red Sox having held a 14-game lead over the Yankees more than halfway through the season. Similarly, the 2004 ALCS is famous for the Yankees leading 3–0 and ultimately losing a best-of-7 series.

In 2019, the rivalry was showcased in the first London Series, with the Yankees winning both games.

The rivalry is often termed the "greatest rivalry in all of sports." Games between the two teams often generate a great deal of interest and get extensive media coverage, including being broadcast on national television. In the stands, it is very common for Yankees fans and Red Sox fans to taunt each other and get into fistfights, so security at both Yankee Stadium and Fenway Park is heavy when either team comes to town.

Boston Red Sox vs. Tampa Bay Rays

The Rays–Red Sox rivalry is contested between the Tampa Bay Rays and Boston Red Sox. Though this rivalry is more recent than the Yankees–Red Sox rivalry, both teams have regularly competed for the AL East title since 2008, winning it a combined seven times between 2008 and 2021. They have also met in the postseason several times, most recently in 2021. Due to this level of close competition, the rivalry has been called one of the most competitive in the modern American League.

American League Central

Cleveland Guardians vs Detroit Tigers

The Cleveland Guardians share a rivalry with the Detroit Tigers fueled by geographic proximity between the two cities, and elements from the intense rivalry between Michigan and Ohio State. The rivalry with came to a head on August 7, 2013, with the teams first and second in the AL Central standings. Many Tigers fans who made the short trip to Cleveland started a "Let's go Tigers!" chant while the game was tied in the ninth inning. Cleveland fans countered with a "Detroit's bankrupt!" chant, in reference to the city's 2013 bankruptcy. Footage of the chants from SportsTime Ohio circulated online, with many baseball fans on social media criticizing Cleveland fans for the chant due to the circumstances of Detroit's financial situation. The Tigers ended up defeating Cleveland 6–5 in 14 innings. The two teams have played almost evenly over their 125-year history with Detroit holding a narrow 1,168–1,167 lead. The teams have met twice in the postseason, with Cleveland winning the 2024 AL Division Series and Detroit winning the 2025 AL Wild Card Series.

Detroit Tigers vs. Chicago White Sox The series between the Detroit Tigers and Chicago White Sox is one of the oldest active rivalries in the Major League Baseball. Both teams joined the American League in 1901 after being charter members of the original Western League. Both have actively played one another annually for over 120 seasons. As is often the case between professional sports teams located in Chicago or Detroit, there usually exists a rivalry as such with the Bulls–Pistons rivalry of the NBA, the Blackhawks–Red Wings rivalry of the NHL, and the Bears–Lions rivalry of the NFL. Despite playing one another for over 2,200 games as of 2026, both teams have yet to meet in the postseason.

Minnesota Twins vs. Chicago White Sox

The Twins–White Sox rivalry is contested between the Minnesota Twins and Chicago White Sox. Though both teams are charter members of the American League, the rivalry did not begin in earnest until the 2000s, when the White Sox and Twins consistently battled for the AL Central crown. In the 2000s, they combined to win 8 out of the 10 AL Central division titles of the decade. Their most prominent meeting occurred in the 2008 American League Central tie-breaker game, which was necessitated by the two clubs finishing the season with identical records.

American League West Lone Star Series: Texas Rangers vs. Houston Astros

The Lone Star Series (also, Silver Boot Series) is a Major League Baseball rivalry featuring Texas' two major league franchises, the Texas Rangers and Houston Astros. It is an outgrowth of the "natural rivalry" established by MLB as part of interleague play as the Rangers are a member of the American League and the Astros were a member of the National League until .

During interleague play, the winner of the 6-game series was awarded the Silver Boot. A tall display of a size-15 cowboy boot cast in silver, complete with a custom, handmade spur. If the series was split (3–3), the winner was the club which scored the most runs over the course of the series.

In , the Astros were forced into the American League West with the Rangers and changed their rivalry from an interleague to an intra-division rivalry, the Astros played their first game in the American League against the Rangers on Sunday Night Baseball that season. In 2015, both teams made the playoffs and were in a tight division race during most of the season.

In 2023, the Rangers and Astros qualified for the postseason, marking the first time since 2015 that both teams made the postseason. While both teams finished the regular season with identical records (90–72), the Astros had the better head-to-head record (9–4). As such, the Astros won their third consecutive division title (and sixth in seven years), whilst the Rangers were relegated to the wild card berth. The two teams had their first postseason matchup in the ALCS. With the visiting team winning every game, the Rangers won the series in seven games en route to their first World Series title, which they achieved by defeating the Arizona Diamondbacks in five games.

Houston Astros vs. Seattle Mariners

The rivalry is relatively new, as the historically National League Houston Astros only joined the American League in the season, joining the American League West, where the Seattle Mariners have played their entire franchise history since . The Astros have been historically dominant against the Mariners, winning nine of their first 13 seasons of matchups (2002, 2004, 2007, 2013–2022). The Astros lead the all-time regular season series 136–104 and have a perfect 3–0 record against Seattle in the postseason.

From 2013 to 2019, the two teams were rarely in contention with each other, with one team making or coming close to making the postseason, while the other was nowhere close. Since 2020, the two teams have grown an increasingly competitive rivalry, having fought handily for control of the division or Wild Card spots, often finishing within five games of each other. The resurgence of the Mariners to playoff contention in 2022 has fueled the rivalry in competition, as difference in records since then has decreased to only three and a half games.