http://www.mentalfloss.com/blogs/archives/51678

The Cincinnati Red Stockings, so named because they wore red socks, were baseball’s first openly all-professional team. In 1882, Cincinnati’s entry in the newly formed American Association took the same name and retained it after moving to the National League in 1890. Red Stockings eventually became Redlegs, and Redlegs was shortened to Reds. Before the 1953 season, club officials announced that the team would once again officially be known as the Cincinnati Redlegs. Around the same time, the team temporarily removed “Reds” from its uniforms. As the AP reported in 1953, “The political significance of the word ‘Reds’ these days and its effect on the change was not discussed by management.”