According to the Transgender Law and Policy Institute, 13 states + DC have some kind of explicit non-discrimination laws: California, Colorado, D.C., Hawaii, Illinois, Iowa, Maine, Minnesota, New Jersey, New Mexico, Oregon, Rhode Island, Vermont, and Washington.

This information comes from their Transgender Issues: A Fact Sheet, which is undated. Their website has quite a few resources and an email address to which you can submit queries.

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