Final answer:
Harvey Milk was the first openly gay person elected to public office in California, and he helped establish the Castro District as a central location for the gay rights movement before his assassination in 1978.
Step-by-step explanation:
The politician who came out openly and became the first openly gay person elected to public office in California, while establishing the Castro District as a hub for the national gay rights movement, was Harvey Milk. Milk was not only a pioneer in LGBTQ rights, but he also played a crucial role in the passage of strong civil rights laws in San Francisco during the 1970s. After winning a seat on the San Francisco Board of Supervisors in 1977, Milk became a leading figure in the gay rights movement before his tragic assassination in 1978.