 Immigrants and others have marched by the thousands down Oakland's International Boulevard in support of legal reforms benefiting undocumented immigrants.An analysis by the Urban Institute of U.S. Census 2000 numbers showed Oakland had the third-highest concentration of gays and lesbians among the 50 largest U.S. cities, behind San Francisco and Seattle.Census data showed that among incorporated places that have at least 500 female couples, Oakland had the nation's largest proportion.