The HCUP variable for the hospital's location and teaching status changed names and definitions across data years:

For H_LOCTCH, the hospital's location and teaching status were obtained from the AHA Annual Survey of Hospitals. A metropolitan statistical area is considered urban, and a non-metropolitan statistical area is rural. Teaching hospitals have an AMA-approved residency program or have membership in the Council of Teaching Hospitals.

Note that a few hospitals classified as rural are also teaching hospitals.