In Harris County today, the first same-sex couple received their marriage license at the courthouse in Houston.
PHOTOS: Reactions to U.S. Supreme Court ruling on same-sex marriage
Dozens of couples showed up at county clerk offices in Austin, San Antonio and Dallas shortly after the decision, which struck down a 2005 state constitutional ban on gay marriage and defied opposition from Texas Gov. Greg Abbott and other Republican leaders.
None of the same-sex couples now receiving licenses will be technically the first to marry in Texas. Earlier this year, a state judge ordered Travis County to issue a marriage license to a lesbian couple, who then wed before Republican Attorney General Ken Paxton had a chance to intervene.
In Travis County, Gena Dawson and Charlotte Rutherford received the county's first same-sex marriage license Friday within two hours of the ruling Friday morning. The license was issued despite the Supreme Court saying the ruling will not take effect until the losing side gets roughly three weeks to ask for reconsideration.
Others in the county clerk's office greeted the ruling with cheers and embraces.
"I never thought this would happen in my lifetime," said Jacque Roberts, who rushed into the clerk's office with her partner of 31 years within minutes of the ruling. "It's still a dream. I can't believe we're doing this in Texas."
Not all counties began issuing marriage licenses right away. In Houston, officials from Harris County were holding off until receiving guidance from the state, which has been at the forefront of Republican resistance in the U.S. as gay marriage became increasingly legal in other states - whether by choice or court order.
The Supreme Court declared Friday that same-sex couples have a right to marry anywhere in the United States, a historic culmination of decades of litigation over gay marriage and gay rights generally. Gay and lesbian couples already could marry in 36 states and the District of Columbia. The court's 5-4 ruling means the remaining 14 states, in the South and Midwest, will have to stop enforcing their bans on same-sex marriage.
Abbott has remained an emphatic opponent of gay marriage, even as signs in recent months pointed to the Supreme Court striking down state bans. Sensing this ruling was coming, the Republican-controlled Legislature earlier this year passed a "pastor protection" law that reaffirmed the rights of clergy members to refuse officiating gay weddings.
Texas law required a three-day waiting period between the issuing of a marriage license and a wedding ceremony, but some judges were expected to grant waivers that would allow gay couples to begin marrying later Friday.
Gay rights groups are also planning celebrations at churches and public squares across Texas, from Amarillo to the Rio Grande Valley.
Texas was not part of the case before the Supreme Court. A federal judge in 2013 ruled that the state's ban on gay marriage was unconstitutional but declined to enforce the ruling while it was on appeal. That case has been pending before the 5th U.S. Circuit Court of Appeals.
The ruling also has the effect of forcing Texas to recognize the marriage of same-sex couples who wed elsewhere. Among those who sued the state was a lesbian couple in Austin who married in Massachusetts.
The Associated Press contributed to this report