A short distance north of Roswell the route turned northwest off of NM 2 and passed through Acme.

In Clovis, the route turned east off of NM 18 and on to US 70 and crossed the state line back into Texas.

[5] At the state line, US 366 reacquired its secondary SH 33 and entered Farwell in Parmer County where it separated from US 70 and headed northeast.

Most of the roadway between Ruidoso and Hondo was merely graded as were two short segments between Acme and Kenna and between Elida and Portales.

[5] As late as 1933, most of the route in the Texas Panhandle was only graded, although the portion between the Deaf Smith-Randall county line to Amarillo was paved.

The route then passed through Clovis, Portales, Roswell, Hondo, Alamogordo, and Orogrande before reentering Texas south of Newman.

The route then continued through El Paso to the U.S.-Mexico border for a total length of 416 miles (669 km).