Baseball Time Machine

SOURCES & DEFINITIONS

Know what the map counts.

Source: SABR / Sean Lahman Baseball Database, credited to Sean Lahman and the database contributors (CC BY-SA 3.0). The archived release covers 1871–2025, including the recognized major leagues and supported Negro League records in its 19 league codes. Earlier and Negro League records have documented gaps; a missing record is not proof that a player or team did not exist. No other professional leagues have been inferred.

24,011 unique players have positive recorded game appearances. Debut cohorts use the first positive appearance year in this database; active cohorts count a player once if any positive appearance falls inside the range. Team changes never multiply that player. Birthplaces describe source birth location, not citizenship. Historical birth countries retain their source identity. 23,078 players have a birth-country entry; unknowns stay visible.

HomeGames determines season-specific venues, with the most recorded home games identifying the primary park. Franchise names and locations follow each historical team season. World Series titles are joined to the winning team’s primary home city that season, including the source’s historical and Negro League World Series records. They are never reassigned to a franchise’s present city.

339 of 345 parks have city-level coordinates. These locate cities, not exact stadium sites. U.S. place coordinates come from the Census 2025 Gazetteer (public domain); international locations use unique GeoNames city matches (CC BY 4.0, attribution GeoNames). Ambiguous matches remain unlocated. City profiles require at least five source players and a reviewed city match; smaller or unlocated groups open the filtered origins atlas.

World outlines: Natural Earth 1:50m map units, public domain. U.S. state outlines: Census via us-atlas. Source licenses apply to their respective inputs and derived data. Download the derived baseball snapshot · Source manifest, retrieval dates and SHA-256 hashes.