It is significant as the main access route (in conjunction with NM 501 and NM 502) connecting the remote town of Los Alamos, Los Alamos National Laboratory, and Bandelier National Monument to other, more major highways in New Mexico.

On the east side of the Jemez Mountains, it descends even more steeply, on a series of hairpin turns offering views into Frijoles Canyon in Bandelier National Monument, to a junction with NM 501 leading east into the town of Los Alamos.

NM 4 itself continues past the main entrance to Bandelier and several Los Alamos National Laboratory sites, as well as the town of White Rock, to another junction with NM 502 east of Los Alamos, where the route ends.

In contrast to several other state highways in northern New Mexico, NM 4 is paved for its entire length.

[3] NM 4 forms the main artery of the Jemez Mountain Trail National Scenic Byway.