Stonewall is one of those great events. Up until Howard Zinn’s People’s History of the United States: 1492 until Present, we thought of history in terms of great leaders and special pivotal events.
But history is far more complicated than that. Pivotal events do not just spring from a vacuum but are more the result of the convergence of a number of elements all building towards that moment.
The riot that happened 40 years ago this weekend had some 20 years of people organizing, agitating, building movements and shifting consciousness. When Stonewall happened it marked the end of one era and the birth of another instead of simply vanishing into an incident forgotten by all except perhaps the participants the way so many acts of resistance from that era are forgotten.
The modern Gay and Lesbian movement started in the late 1940s after World War II had called so many to serve. And gay men as well as women served. Transsexuals too, Christine Jorgensen was in the military.
When they returned home many stayed in the big cities of San Francisco, Los Angeles, New York. They stayed because they had learned during their time in the military that they were gay and lesbian and these cities offered contact with others like themselves.
In 1949, Harry Hay, Dale Jennings, Rudi Gernreich Chuck Rowland, Paul Bernard and other gay men founded the Mattachine Society in Los Angeles.
They came together to struggle for gay right even though they didn’t start using that term until years later. They used the term “homophile” because censorship prevented even the use of the term homosexual for purposes of placing classified ads in order to announce meetings. This also permitted the mailing of their newsletters and publications at a time when postal authorities censored mail for even using the term “homosexual”, much less discussing it.
In San Francisco several years later Del Martin and Phyllis Lyon organized Daughters of Bilitis, the first modern lesbian organization.
From these two groups as well as groups who broke off from these groups sprang the modern Gay and Lesbian movement.
At first, they had modest goals including simply being there to show others they were not alone. In this regard, they published newsletters (magazines). The Mattachine published One and Daughters of Bilitis published The Ladder.
The forces of censorship required a certain degree of subterfuge in the distribution of these newsletters and eventually led to the Mattachine society having to fight a legal case to win their right to send the newsletter through the US Mail.
About this time, Christine Jorgensen got her surgery in Denmark. She wasn’t the first and she wasn’t the only one changing sex in the early 1950s. 
In cities across the nation there was a lively and only semi under ground bar scene. Sometimes in the gay and lesbian meccas of cities like Los Angeles and San Francisco, sometimes in unlikely locations such as Buffalo, NY.
Fire Island was the gay vacation place and a summer party for gay men from the 1950s onward.
Thanks to the efforts of Virginia Prince and another cross dresser known as Susanna there was the start of what evolved into the heterosexual organized cross dressing scene complete with resorts and conferences.
 Timmons, Stuart; The Trouble with Harry Hay Alyson Pub Boston 1990
 Gallo, Marcia; Different Daughters: A History of the Daughters of Bilitis and the Rise of the Lesbian Rights Movement Seal Press 2007
 Meyerowitz, Joanne; How Sex Changed: A History of Transsexuality in the United States Harvard University Press 2004
 Stryker, Susan; Van Buskirk, Jim and Maupin, Armistead; Gay by the Bay: A History of Queer Culture in the San Francisco Bay Area Chronicle Books 1996
 Kennedy, Elizabeth; Davis, Madeline; Boots of Leather, Slippers of Gold: The History of a Lesbian Community Routledge 1993
 Newton, Esther; Cherry Grove: Fire Island Beacon 1993