Originally, station agents were on duty 24 hours a day; conductors were used on the Logan Square, Humboldt Park, and Northwest branches to instead collect fares on trains during night and off-peak hours from 1931 through 1937, except for the Northwest branch in 1935. They returned to the Milwaukee branch in 1950, and continued in use until 1995.
Initially, station agents were responsible for all operations at stations; however, from 1931 to 1937, conductors were used on specific lines (Logan Square, Humboldt Park, Northwest) to collect fares during off-peak hours and nighttime. This practice ended in 1935 for the Northwest branch, but resumed in 1950 for the Milwaukee branch until 1995.