MEXICO CITY - Mexico will send a diplomatic letter to the United States protesting the extension of a wall along the U.S.-California border, officials said Friday. Ruben Aguilar, a spokesman for President Vicente Fox, said the president would also continue to pressure the U.S. government to approve a migration accord that would allow more migrants to work legally north of the border. President Bush proposed a temporary work program last year, but it has stalled amid opposition in Congress. Mexican Foreign Secretary Luis Ernesto Derbez said Thursday that Fox had instructed him to send the diplomatic letter with the message...