Billie Jean King defeated Rosemary Casals in the final, 6–4, 7–6(5–2) to win the women's singles tennis title at the 1971 US Open. Margaret Court was the two-time reigning champion, but did not defend her title. This tournament marked the first major in which future world No. 1 and 18-time major champion Chris Evert competed in the main draw; she lost to King in the semifinals. Evert competed in 19 consecutive US Opens until her retirement in 1989, and failed to reach the semifinals only twice in that span.