Acknowledging many of its citizens in the United States lead risky lives without medical coverage, the Mexican government will unveil a new program next month offering them unprecedented access to treatment — back home. Meant as a move to improve both health care and relations with its northern neighbor, the program actually is an extension of Mexico's Seguro Popular, a national low-cost health care system akin to Medicare. The government covers most of the cost. About 400,000 migrants are expected to be eligible this year, said Juan Fernández Ortiz, a national health commissioner in charge of the program. He said...