Beginning: Baltimore (1901-1902)

In late 1900, Western League president Ben Johnson reorganized the league, adding teams from three eastern cities to form the American League. Plans to locate a team in New York City were blocked by the National League`s New York Giants (now based in San Francisco and called the San Francisco Giants ), who had enough political clout to keep them out of the American League. Instead, the team was placed in Baltimore, Maryland, a city that had been left out of competition in 1900 when the National League was reduced from 12 to eight teams.

The team began playing under the name Orioles in 1901, managed by John McGraw. McGraw feuded with Johnson throughout the 1902 season and secretly defected to the Giants. Midway through the season, McGraw assisted and advised the Giants, while still looking out for the Orioles` interests and began to convey them to the players until the American League stepped in and took control of the team. In January 1903, a ``peace conference`` was held between the two leagues to resolve their differences and attempt to coexist. At the conference, Johnson demanded that an American League team be located in New York City and play parallel to the National League Giants. In a vote, 15 of the 16 major league team owners agreed to this, with Giants owner John T. Brush the only opponent. As a result, the National League agreed to the decision to establish the club in New York. The new owners of the Orioles, Frank J. Farrell and William S. Devery, began construction of the stadium, the location was not protested by the Giants, and the team moved from Baltimore to New York.

Their rivalry with the Boston Red Sox is arguably the most oldest in the history of North American professional sports.