The present paper examines aggregate player movement in Major League Baseball over the majority of the 20th century. Major League Baseball has been subject to numerous exogenous shocks across the period. For example, it has been subject to competition during the mid-1910s with the introduction of the Federal League. It has also changed its own rules such as racial integration, free agency, and revenue sharing. In order to examine the impact that these shocks have on player movement we examine movement over three dimensions: total players, total at-bats, and total innings. In the end we find that free agency, racial integration, and revenue sharing increased player movement.