It's been talked about in their recent anthology special,on TV
Wikipedia has a short summary
"....The song is about trying to write a song in the middle of the night. The song's writer, Robert Lamm, had recently written another Chicago hit, "Does Anybody Really Know What Time It Is?", and this title serves as the answer.
It's the time of day in which the song is set: 25 or 26 minutes before 4 AM.[2]
Because of the unique phrasing of the song's title, "25 or 6 to 4" has been incorrectly speculated to be a veiled reference to drug quantities, or a mystical allusion.[3]
The 1986 music video for the song references the correct meaning at its beginning..."
Wikipedia has a short summary
"....The song is about trying to write a song in the middle of the night. The song's writer, Robert Lamm, had recently written another Chicago hit, "Does Anybody Really Know What Time It Is?", and this title serves as the answer.
It's the time of day in which the song is set: 25 or 26 minutes before 4 AM.[2]
Because of the unique phrasing of the song's title, "25 or 6 to 4" has been incorrectly speculated to be a veiled reference to drug quantities, or a mystical allusion.[3]
The 1986 music video for the song references the correct meaning at its beginning..."