Business Interstate Highway 40-A (formerly Spur 504) is a Business Spur that runs from I-40 at Glenrio, just east of the New Mexico state line, southwest to the border. In New Mexico, the road forks - the later paved alignment (c. 1952) has been cut by Interstate 40, and the earlier alignment west to San Jon is now a dirt road that had been paved when it was US 66 prior to 1952 but the paving was later removed by Quay County, NM commissioners due to high maintenance costs and low traffic volumes. The old US 66/I-40 Business Loop through Glenrio was bypassed in 1973 by I-40.