Aug 1, 2013— Same-sex marriage became legal in Rhode Island and Minnesota by State Legislature
Aug 3, 1974—Lesbian Connection Begins Publication
Aug 4, 2010—Chief U.S. District Judge Vaughn Walker from the United States District Court/Northern District of California decides that Perry v. Schwarzenegger (pro 8) is unconstitutional
Aug 5-21, 2016—A record number of “out” athletes compete in the summer Olympic Games in Rio de Janeiro. The Human Rights Campaign estimates that there are at least 41 openly lesbian, gay and bisexual Olympians – up from 23 that participated in London 2012.

Aug 5, 2004—A Washington judge rules the state’s law defining marriage is unconstitutional
Aug 6. 1994—Japanese American Citizens League Supports Same-Gender Marriage
Aug 8, 1978—International Lesbian and Gay Association is founded
Aug 11-18, 1968—NACHO formally becomes the first gay political coalition
Aug 12, 2004—The California Supreme Court orders San Francisco officials, including Mayor Gavin Newsom, not to license additional same-sex marriages.
Aug 16, 2008—Ellen & Portia married at their home, with 19 guests including their mothers.
Aug 20, 2011—Chely Wright married LGBT advocate Lauren Blitzer in a private ceremony  on a country estate in Connecticut by both a rabbi and a reverend.
Aug 20-22, 1976—Michigan Womyn’s Music Festival holds its first gathering.
August 21, 2014—The US District Court for the Northern District of Florida ruled the state’s same-sex marriage ban unconstitutional. Same-sex marriage has been legal in Florida since January 6, 2015, as a result of a ruling in Brenner v. Scott from the same court.
Aug 26, 1969—Canada decriminalizes homosexual acts.
Aug 28, 1985—Desert Hearts, a lesbian-themed romantic drama film loosely based on the Jane Rule novel, Desert of the Heart, is released.
Aug 29, 1867—Karl Heinrich Ulrichs speaks publicly for gay and lesbian rights.
Aug 29, 2013—The U.S. Treasury Department rules that legally married same-sex couples will be treated as married for tax purposes, even if they live in a state that doesn’t recognize same-sex marriage.
Aug, 1971—Lesbian Tide, the first lesbian news periodical is published.
Aug, 1973—American Bar Association calls for repeal of laws against consensual sex.

Sources: Historic Calendar project, Wikipedia, Library of Congress, Gay and Lesbian Issues, CNN.