MazatlÃ n , with a population of 352,471 ( city ) and 403,888 ( municipality ) as of the 2005 census , is the second-largest city in the state ( after CuliacÃ n ) and Mexico 's largest commercial port . MazatlÃ n , with a population of 438,434 ( city ) and 489,987 ( municipality ) as of the 2010 census , is the second-largest city in the state ( after CuliacÃ n ) and Mexico 's largest commercial port .