Counterculture of the 1960s: The Human Be-In takes place in San Francisco, California's Golden Gate Park, launching the Summer of Love.

The counterculture of the 1960s was an anti-establishment cultural phenomenon and political movement that developed in the Western world during the mid-20th century. It began in the mid-1960s, and continued through the early 1970s. It is often synonymous with cultural liberalism and with the various social changes of the decade. The effects of the movement have been ongoing to the present day. The aggregate movement gained momentum as the civil rights movement in the United States had made significant progress, such as the Voting Rights Act of 1965, and with the intensification of the Vietnam War that same year, it became revolutionary to some. As the movement progressed, widespread social tensions also developed concerning other issues, and tended to flow along generational lines regarding respect for the individual, human sexuality, women's rights, traditional modes of authority, rights of people of color, end of racial segregation, experimentation with psychoactive drugs, and differing interpretations of the American Dream. Many key movements related to these issues were born or advanced within the counterculture of the 1960s.

The Human Be-In was an event held in San Francisco's Golden Gate Park Polo Fields on January 14, 1967. It was a prelude to San Francisco's Summer of Love, which made the Haight-Ashbury district a symbol of American counterculture and introduced the word "psychedelic" to suburbia.

San Francisco, officially the City and County of San Francisco, is a commercial, financial, and cultural center of Northern California. With a population of 827,526 residents as of 2024, San Francisco is the fourth-most populous city in the U.S. state of California and the 17th-most populous in the United States. San Francisco has a land area of 46.9 square miles at the upper end of the San Francisco Peninsula and is the fifth-most densely populated U.S. county. Among U.S. cities proper with over 250,000 residents, San Francisco is ranked first by per capita income and sixth by aggregate income as of 2023. San Francisco anchors the 13th-most populous metropolitan statistical area in the U.S., with almost 4.6 million residents in 2023. The larger San Jose–San Francisco–Oakland combined statistical area, the fifth-largest urban region in the U.S., had a 2023 estimated population of over nine million.