After leaving the national forest, the road continues east for approximately 13 more miles before merging with US 285 at Antonito.

From Antonito, SH 17 runs northward concurrent with US 285 for just over thirty miles to the city of Alamosa.

The route then reappeared northeast and terminated at SH 15 (now moved) near Mineral Hot Springs.

The portion of the eastern segment from the New Mexico state line to Antonito was deleted and readded by 1938 and 1946, respectively.

[2] ^ a: The section of SH 17 which runs concurrent to US 285 is maintained with federal rather than state funds and is therefore not counted by the Colorado Department of Transportation in the road's official 88.5 mile length; the total end-to-end length including this segment is 118.8 mi (191.2 km).