Discuss as:

Mary Cheney, daughter of former vice president, marries longtime girlfriend

Charlie Neibergall / AP

Mary Cheney, left, daughter of former Vice President Dick Cheney, with her partner, Heather Poe, at the Republican National Convention in New York in September 2004.

Mary Cheney, daughter of former Vice President Dick Cheney, and longtime partner Heather Poe have married in Washington, D.C., the family confirmed on Friday.

"Very happy to announce that as of this morning, Heather and I are legally married (at least in DC), 20 years to the day after our first date,” Mary Cheney posted on her Facebook page.

The former vice president and his wife, Lynne, were “delighted," according to a statement provided to The Daily Caller.

"Mary and Heather have been in a committed relationship for many years, and we are delighted that they were able to take advantage of the opportunity to have that relationship recognized," the statement said, according to the Caller. "Mary and Heather and their children are very important and much loved members of our family and we wish them every happiness."

Poe and Mary Cheney have two children, a son and daughter born to Cheney.

They live in Virginia.

Same-sex marriage was legalized in the District of Columbia in December 2009. The district began issuing licenses in March 2010.

NBC News Jamie Gangel contributed to this report.

More content from msnbc.com and NBC News:

Follow US News on msnbc.com on Twitter and Facebook

Follow Kari Huus on Facebook