Team Codes, Franchises and Name Changes Explained

The Atlanta Braves began as the Boston Red Caps in 1876. In between they were the Beaneaters, Doves, Rustlers, Braves, Bees, Braves again and the Milwaukee Braves. Any baseball database has to decide what to call a club in each of those years and how to keep its history together. This guide explains how Baseball Data Hub does it.

Three kinds of team page

The site has three levels of team page, and each answers a different question.

• A team-season page, such as /teams/bsn/1936, covers one club in one year: its record, roster, batting and pitching tables and postseason results. It uses the name the club had that season, so this page is the 1936 Boston Bees.
• A team code page, such as /teams/bsn/, lists every season played under one team code. It is titled with the most recent name used with that code.
• A franchise page, such as /franchises/atl, follows one continuous franchise through every code, name and city it has had, with its all-time record, championships and notable players.

What the codes mean

The three-letter codes come from the Lahman Baseball Database, the main historical source for the site. Lahman gives each club a team ID that stays fixed while the club stays in one city: NYA for the New York Yankees, CHA for the Chicago White Sox, BSN for the Boston National League club, ML1 for the Milwaukee Braves of 1953 to 1965. When a club moves, it gets a new team ID but keeps its franchise ID, which is what ties Boston, Milwaukee and Atlanta together.

Several of the Lahman IDs differ from the abbreviations used on broadcasts today. The site recognizes both, so NYA and NYY, CHA and CHW, and SLN and STL each refer to the same club. Current-season data from the MLB Stats API uses MLB's own codes, such as AZ, ATH, CWS and WSH, and these are matched to the same franchises.

Contemporary names, not current ones

A record should be labelled with the club that held it at the time. Walter Johnson won the 1924 American League MVP award pitching for the Washington Senators. The franchise has been the Minnesota Twins since 1961, but calling Johnson a Twin would describe a team that did not exist until fifteen years after his death. Everywhere a player's season is listed, including profiles, award pages and leaderboards, the site uses the club and code of that season.

The franchise code is kept alongside for grouping, which is how the Twins franchise page still includes the Washington years.

Some franchises worth following

• Braves: Boston (1876–1952), Milwaukee (1953–1965), Atlanta (1966 on). One franchise and three team codes, BSN, ML1 and ATL.
• Athletics: Philadelphia (PHA, from 1901), Kansas City (KC1, from 1955), Oakland (OAK, from 1968) and, since leaving Oakland in 2025, simply the Athletics (ATH). All four belong to the Athletics franchise.
• The two Washington Senators: the original Senators (WS1, 1901–1960) became the Minnesota Twins. An expansion club, also called the Washington Senators (WS2, 1961–1971), became the Texas Rangers. The two clubs share a name and a city but are separate franchises, and the codes keep them apart.
• Expos and Nationals: the Montreal Expos (MON, 1969–2004) moved to Washington as the Nationals (WAS) in 2005. They are one franchise, unrelated to either Senators club.

More moves and renamings

The same pattern runs through most of the older franchises. A few that often cause confusion:

• Dodgers: the Brooklyn club was the Atlantics, Grays, Bridegrooms, Grooms, Superbas and Robins before the Dodgers name settled in 1932. It moved to Los Angeles in 1958, changing its code from BRO to LAN.
• Giants: the New York Gothams became the Giants in 1885 and moved to San Francisco in 1958, from code NY1 to SFN.
• Orioles: the American League's Milwaukee Brewers of 1901 became the St. Louis Browns in 1902 and the Baltimore Orioles in 1954. They have no connection to today's Milwaukee Brewers.
• Brewers: today's Brewers began as the Seattle Pilots in 1969 and moved to Milwaukee in 1970 as ML4. When they switched from the American League to the National League in 1998 their code became MIL, although the club did not move.
• Yankees: the franchise began in 1901 as an American League club in Baltimore, moved to New York as the Highlanders in 1903 and took the Yankees name in 1913.
• Astros: the Houston Colt .45's became the Astros in 1965 under the same code, HOU, so the name changes within one team code page.

One code, two eras

A code can also come back. LAA was the code of the Los Angeles Angels in their first seasons from 1961. The club then played as the California Angels (CAL) and the Anaheim Angels (ANA), and when it took back the Los Angeles name in 2005 it took back LAA as well. The LAA team code page therefore holds two separate runs of seasons, decades apart, while the franchise page shows the whole history in order, including the CAL and ANA years between them.

Why the code page and the franchise page can disagree

A team code page and a franchise page can show different all-time records for what sounds like the same club, because they cover different spans. The /teams/bsn/ page covers only the Boston seasons; the Braves franchise page adds Milwaukee and Atlanta. Neither is wrong, and each page states the years it covers.

Other leagues

The same system covers clubs from the nineteenth-century major leagues and, on player and team pages, the Negro Leagues, whose clubs often changed names, cities and leagues more often than AL and NL clubs did. The Negro Leagues guide describes that data. For every club on the site, start at the teams directory or the franchise list.