PUERTO PENASCO, Mexico — Mexican President Felipe Calderon told U.S. governors Thursday that immigration is an inevitable, natural phenomenon and he urged the U.S. Congress to approve reforms that would allow more Mexicans to work legally north of the border. Calderon demanded that the United States respect "the right to work wherever one can make the greatest contribution." "Immigration is a natural phenomenon that is economically and socially inevitable," he told the meeting in this Baja California seaside resort town. In a rare acknowledgment of the costs of migration for Mexico, Calderon said his country "doesn't not celebrate migration ......