This is a common belief, that the name "Dotsero" is related to the mileposts on the D&RGW. However, the first recorded instances of that location being called such occur in 1883, in a letter referring to the confluence of the Grand (now Colorado) and Eagle rivers. However, the D&RGW did not reach the area until 1887 and the station name did not appear on timetables until 1902. Most commonly the idea of this being the origin stems from the Dotsero cutoff, but this was not started until 1924 (with the construction of the Moffat Tunnel) but was not completed until 1934, once the D&RGW took control of the D&SL. But since the name Dotsero existed nearly 40 years prior to the start of the cutoff which now bears its name, it is fairly clear the name has nothing to do with the mileposts on the railroad.

The origin of the name Dotsero is unknown, with many theories being advanced as to where it came from, inclduing Ute indian words, the railroad, and so forth, but the leading theory is that it is based on some original surveys completed in the area, which may have used it as it starting point (so there might be a loose connection to a concept of milepost 0).