Equality before the law, a funny sort of thing, grinds slowly forward - and to my associate on Facebook who asked "State by State? How's that gay marriage thing working out for you?" ...my answer is pretty damned well.
It's not been all roses and sunshine, certainly, but beginning in the dark days of 1993 (well, more the light gray days, really...'93 was still a screaming improvement over pre-Stonewall) with a ruling by the Supreme Court of Hawaii that the pre-existing ban on LGBT marriage was unconstitutional - followed by the people of Hawaii amending their constitution just so the state legislature could reinstate the ban.
Massachusetts - May 17, 2004
The next big change was again the result of a court decision, Goodridge vs. MA Dept' of Public Health, where it was ruled in part "Barred access to the protections, benefits, and obligations of civil marriage, a person who enters into an intimate, exclusive union with another of the same sex is arbitrarily deprived of membership in one of our community's most rewarding and cherished institutions. That exclusion is incompatible with the constitutional principles of respect for individual autonomy and equality under law."
Although the U.S. District Court in Boston ruled in two related cases on July 8, 2010, that the provisions of the federal Defense of Marriage Act barring federal recognition of legally married same-sex couples are unconstitutional, the final judgment is stayed pending the federal government's appeal to the First Circuit Court of Appeals. Such an appeal was filed on October 12, 2010, by the U.S. Justice Department; consequently, Massachusetts same-sex couples are not eligible to receive federal recognition of their marriages, pending the outcome of the appeals process.
California June 16, 2008 - November 5, 2008, ?
The period of granting such licenses began on June 16, 2008, due to a ruling by the Supreme Court of California based on an equal protection argument and ended November 5, 2008, due to the passage of Proposition 8, an amendment to the California Constitution that limited marriages to those between one man and one woman (Wikipedia).
Subsequently, Proposition 8 has been ruled unconstitutional by U.S. District Court Judge Vaughn Walker (now retired) - this decision, however, has been stayed pending further appeals.
Another victory by judicial fiat, the Supreme Court of the State of Connecticut struck down that states Civil Union law and ruled that same sex couples have the constitutional right to marry.
Iowa - April 3, 2009
Again by judicial fiat, the Supreme Court of the State of Iowa ruled that same sex couples have the same right to marry as couples of differing genders.
More recently in Iowa, an attempt to amend that states constitution to bar same sex marriage was passed by the Iowa House of Representatives - it faces a stiffer fight in the Iowa Senate, and must survive a vote by the people before taking effect.
Maine - May 6, 2009-November 3, 2009
Passed into law on and signed by then-Gov. Balducci on May 6, 2009 same sex marriage was repealed by voters on Nov. 4, 2009.
New Hampshire - June 3, 2009
In the first legislatively passed acknowledgement of LGBT marriage rights, famously conservative New Hampshire passed landmark legislation with the proviso that no religious institution could be sued for refusing to perform marriages repugnant to their faith.
GOP Conservatives, determined to lose the 2012 presidential race, promise to make LGBT marriage an issue in that states primary and to attempt to repeal the laws authorizing it in 2012.
Vermont Approved - April 7, 2009 Effective: September 1, 2009
Arguably the first state to pass same sex marriage legislatively, the Vermont legislature passed the authorizing legislation over the governors veto on April 7 of 2009.
Washington, D.C. - December 18, 2009
legalized on December 18, 2009, when mayor Adrian Fenty signed a bill passed by the Council of the District of Columbia on December 15, 2009. Following the signing the measure entered a mandatory Congressional review of 30 work days. Marriage licenses became available on March 3, 2010, and marriages began on March 9, 2010. The District became the only jurisdiction in the United States below the Mason–Dixon Line to allow same-sex couples to marry. (Wikipedia)
New York June 24, 2011 (Takes effect July 24th, 2011)
The hostiles are circling their wagons, but right now it looks like New York is going to be the ninth major jurisdiction to legalize gay marriage...and hopefully the 7th to keep it!!