People always think we're jamming GPS near the border, but all those yellow and red hexes are in the Laughlin and Randolph military operating areas (MOAs). It's much more likely to either be military testing/training involving systems that cause GPS interference, or jet fighter training where aircraft maneuver so hard their GPS antennas are masked from satellites by the body of the aircraft.

Map showing the possible interference overlaid on an FAA sectional chart showing the MOAs: https://i.imgur.com/vieGhgN.png