Then as now, left-handed batting outfielders were in high demand and Boots Day was also a fast running base runner. He started in the minors at Rock Hill of the Western Carolina League in 1966 and worked his way up the ladder playing for teams at St Petersburg, Arkansas and Tulsa before being brought up to the majors in late-1969 by St Louis. After playing in 11 games with the Cardinals, Charles Day was traded on December 4 1969 to the Cubs for pitcher Richard Nye, then after playing 11 games in the Windy City he was traded to the Expos on May 12 1970 for catcher Jack Hiatt.
Boots Day had four productive seasons in Montreal from 1970-73, hitting .269, .283, .233 and .275. A contact hitter he only struck out around once every 10 at bats.