Originally Posted by doublem23
No, when the Dan Ryan branch was built it was part of the Green Line, with trains running from 95th to Harlem in Oak Park via the Loop, whereas the North Side Red Line was paired with the Englewood/Jackson Park forks. They didn't switch them until they built the connection from the State Street Subway to the Dan Ryan branch in the early 90s when they built the elevated Roosevelt station.
CTA Map from 1991 shows the old configuration: http://www.chicago-l.org/maps/route/maps/1991map.jpg
CTA didn't start calling the lines by colors until 1993, when they realigned the through routes. So saying the Dan Ryan line was originally part of the Green Line is incorrect or at least misleading. When the Dan Ryan line opened it was part of the West-South route (Lake-Dan Ryan) while the North-South route was Howard-Englewood/Jackson Park:
The system map color-coded the lines in 1985 (http://www.chicago-l.org/maps/route/maps/1985map.jpg
) but the routes weren't called by those colors; in fact, green was generally the color used for "B" stop station signage from 1969 (when the Dan Ryan line went into revenue service) until 1995 (when all skip stops were eliminated). Red was the "A" stop sign color and blue was used for "A/B" stops.