Northwestern Corner of Texas
At the intersection of US-56/US-64/US-412 and Texas State Line Rd / Rinker Rd.
36°30'01.4"N 103°02'29.8"W == 36.500382N 103.041602W

At the corner of US-56/US-64/US-412 and Texas State Line Rd / Rinker Rd

At the corner, looking southeast.

Looking southeast.

Looking southeast.

The Department of the Interior survey disk.

At the corner of US-56/US-64/US-412 and Rinker Rd, looking northeast.

The Department of the Interior survey disk in a small hole.

The Department of the Interior survey disk.

Another survey disk, maybe at NW corner also. Photo from Google Maps.

Google Maps

Google Maps

Google Maps

Google Earth

Google Earth

Garmin MapSource

On the survey marker on the concrete slab by the fence line:
U.S. Department of the Interior, Bur. of Land Management
Unlawful to disturb. Cadastral Survey.
RM TEXAS (arrow symbol) 41.19 FT TO COR, 1991

On the survey marker in the dirt by the highway:
U.S. Department of the Interior, Bur. of Land Management
Unlawful to disturb. Cadastral Survey.
NEW MEXICO (corner symbol) NW COR TEXAS, 1991

On the survey marker maybe at the NW corner also:
U.S. Department of the Interior, Bur. of Land Management
Unlawful to disturb. Cadastral Survey.
RM NEW MEXICO,(arrow symbol) 111.59 FT TO COR, 1991

Concerning the "crooked" eastern border of New Mexico at the northwestern corner of Texas and Clarks Monument, check:
texasstandard.org article "How A Bad Survey And Powerful Connections Added 1,000 Square Miles To Texas’ Lands"
Brock, Ralph H. “Perhaps the Most Incorrect of any Land Survey in the United States”, Southern Historical Quarterly, April 2006, pp. 431-462.
Haley, J. Evets. The XIT Ranch of Texas and the Early Days of the Llano Estacado, University of Oklahoma Press, 1953.
Hoover, Mike. “The Southeast Corner of New Mexico.” The Texas Surveyor, May, 2015, pp. 16-23.