The agency that regulates broadcasting in Mexico, CoFeTel has approved the use of HD Radio for both AM and FM stations withing 320 km of the US Border. The news reports did not mention whether night operation by AM stations was authorized.
Official statement (translated):
“Considering the extent of the development and implementation of the IBOC system in the United States of America, Mexico is required to take decisive action so that [the country’s AM and FM radio stations] in the zone located within 320 kilometers of the northern border of Mexico can transmit at the same technological level so that they can provide the benefits of quality service to the radio listening public.”