US-56/64/412 enter Oklahoma near the southwest corner of the Panhandle, where they also enter Rita Blanca National Grassland. US-56's short path through Oklahoma consists of a diagonal slice across the western part of the Oklahoma Panhandle. The three routes then cross into Oklahoma together. The three routes serve as the southern terminus of NM 406 as they enter the Kiowa National Grassland. US 56/412 intersect US 64 and US 87 in Clayton, New Mexico, and US 64 joins with US 56/412 in their trek northeast. Continuing east, US 56/412 meet the southern terminus of NM 193 south of Farley, the northern terminus of NM 120 east of Gladstone, and the southern terminus of NM 453.
The two routes begin in Springer and head east towards Abbot, where they serve as the northern terminus of State Road 39. US 56 runs concurrent with US 412 for its entire length in New Mexico, and are signed as such through the state. The eastbound shoulder also touches a corner of Texas at a small road junction near the New Mexico/Oklahoma border. The highway passes through New Mexico, Oklahoma, Kansas, and Missouri.
