United officials say they regret Parker's inconvenience.
Parker and her two daughters Friday arrived early at San Francisco International Airport but faced a long check-in line. Parker checked in the girls, but time expired for the mayor to check in.
Parker says a gate agent said the person not checked in couldn't travel.
Parker noted she was with two minors. The family took a later flight.
Parker on Saturday tweeted: "Just landed from spring break trip with girls. 1.5 hours late leaving Houston and 8 hours late coming back from SF. Great merger, United!"
United and Continental merged in 2010. United opposes a Southwest Airlines plan for international flights from city-operated Hobby Airport.
