Doesn't look like anyone ever did Colorado in this thread. We can categorize those that we're missing under 100 like so:
Don't Currently Exist to Prevent Confusion with U.S. Highways or Interstates
CO6, CO24, CO25, CO34, CO50, CO70, CO84, CO85, CO87
Used To Exist But Don't Share Numbers with Current U.S. Highways or Interstates
CO4 - Became I-70 and US24 between Utah and Kansas
CO19 - Became US550 between New Mexico and Montrose
CO20 - Became US50, BL70, and US6 near Grand Junction
CO31 - Became County Line Road (between Arapahoe and Douglas Counties)
CO43 - Was a spur from US24 to Bethune, currently CR40
CO48 - Was a spur from CO109 (now CR109) west near Hugo (don't know which road it is currently)
CO49 - Became US36 between Denver and Boulder
CO54 - Became US34 between Brush and Nebraska
CO73 - Downgraded to Jefferson CR 73
CO77 - Downgraded to Park CR77
CO81 - Became I-76 between Denver and Wiggins
CO98 - Became CO74 between Evergreen and Brookvale
CO99 - Became CO142 between San Luis and Costilla CR10, and then CR10 down to New Mexico