When Did MLB Baseball Start? Key Dates Explained

By Sarah Miller · May 22, 2032

Major League Baseball (MLB) officially began on April 22, 1876, with the first game played between the Boston Red Stockings and the Chicago White Stockings of the National League, marking the foundation of professional baseball as we know it today.

The Origins of Major League Baseball

The birth of Major League Baseball is rooted in the formal establishment of the National League in 1876. While organized baseball games existed earlier, the formation of the National League marked the beginning of a structured, professional league that excluded amateur players and set standards for team ownership, scheduling, and competition.

Key Factors Leading to MLB's Formation

Rise of professional play in the 1860s, especially after the Civil War
Dissatisfaction with the National Association of Professional Base Ball Players (1871–1875)
Demand for stronger governance, reduced gambling influence, and consistent schedules
Leadership of William Hulbert, who founded the National League

Evolution of the Modern MLB Structure

While the National League started in 1876, the modern structure of MLB emerged through key developments over more than a century. The American League was established as a major league in 1901, and the first World Series was played in 1903, solidifying the two-league system.

Milestones in MLB History

1876: National League founded with eight charter teams
1901: American League declared itself a major league
1903: First World Series between Boston Americans (AL) and Pittsburgh Pirates (NL)
1969: Introduction of divisions and League Championship Series
1997: Introduction of interleague play
1998: Expansion to 30 teams (current number)

Year	Event	Teams Involved	Significance
1871	National Association founded	Philadelphia Athletics, New York Mutuals, etc.	First professional baseball league
1876	National League founded	Boston Red Stockings, Chicago White Stockings	Start of MLB; more stable structure
1901	American League established	Chicago White Sox, Detroit Tigers	Rival major league formed
1903	First World Series	Boston Americans vs. Pittsburgh Pirates	Unification of AL and NL
1998	Final expansion	Tampa Bay Devil Rays, Arizona Diamondbacks	Reached current 30-team format

Table data source:1, 2

The data highlights how MLB evolved from a single league into a national institution. The 1876 founding remains the recognized starting point because it introduced sustainable governance absent in the earlier National Association. The addition of the American League in 1901 created the dual-league framework still used today.

Why 1876 Is Considered MLB's Start Date

Although professional baseball existed before 1876, the National League’s creation is seen as the true beginning of MLB due to its enduring structure, centralized authority, and exclusion of amateur clubs. Unlike the National Association, which lacked enforcement power, the NL enforced contracts, standardized rules, and penalized teams for misconduct—hallmarks of a major professional league.

Criteria That Define MLB's Official Start

Professional exclusivity and player contracts
Centralized league management
Regular season scheduling and standings
Long-term franchise stability
Exclusion of ad hoc or amateur teams

Frequently Asked Questions About When MLB Started

When did professional baseball start in the United States?

Professional baseball began in 1869 when the Cincinnati Red Stockings became the first openly all-professional team. They toured the country and popularized paid play, leading to the formation of the National Association in 1871, the first professional league.

Was the National Association part of MLB?

No, the National Association of Professional Base Ball Players (1871–1875) is not officially recognized as part of MLB history. Although it was the first professional league, it lacked strong governance, had inconsistent schedules, and allowed gambling influence, which led to its replacement by the National League in 1876.

When did the American League join MLB?

The American League was established as a major league in 1901, declaring itself equal to the National League. After a brief period of rivalry, the leagues agreed to cooperate, culminating in the first World Series in 1903.

What was the first MLB game ever played?

The first official National League game—recognized as the start of MLB—took place on April 22, 1876, between the Boston Red Stockings and the Chicago White Stockings. Boston won 6–5. This game marked the beginning of organized, professional league play under the NL’s authority.

How has MLB expanded since its founding?

MLB began with 8 teams in 1876. It expanded gradually: to 16 teams by 1901, 20 by 1961, 26 by 1977, and reached its current 30-team structure in 1998 with the addition of the Arizona Diamondbacks and Tampa Bay Devil Rays. Expansion brought teams to new markets like Los Angeles, Toronto, and Miami.