As a rule, today JCCs are open to other ethnic groups as well, with possible exception of strictly traditional Jewish activities.
History
The YMHA (Young Men's Hebrew Associaton) was first set up in 1854 in Baltimore to provide help for Jewish immigrants. A YWHA (Young Women's Hebrew Association) was first established as an annex to the YMHA in New York in 1888, and the first independent YWHA was set up in 1902. In 1917 these organizations were combined into a Jewish Welfare Board, and were later renamed Jewish Community Center (or JCC) (though some retain the YWHA or YMHA designation).