Salina Cruz, Mexico – At Mexico's narrowest point, between the Pacific and Atlantic oceans, the government is building a railway to rival the Panama Canal, with promises of economic bounty but amid fears of environmental and social harm.The Spanish conquistador Hernan Cortes had dreamed of such a crossing for humans and goods in the 16th century, but most plans came to naught and a prior, rudimentary connection was all but abandoned with the opening of the canal cutting through Panama in 1914.Th...