Hillary Rodham Clinton said she was going to hit the road. And she did.

Around the time a video was posted announcing her candidacy for president, Mrs. Clinton began a two-day drive to Iowa where she is scheduled to have her first campaign event on Tuesday.

The surprise road trip was Mrs. Clinton’s idea and would not have been made public had someone who saw her at a gas station in Pennsylvania not alerted CNN, an aide said. The aide added that Mrs. Clinton wanted to visit with people at rest stops and diners along the way.

In the announcement video, Mrs. Clinton said she would be “hitting the road to earn your vote.”

On Sunday evening, Mrs. Clinton posted a message on Twitter — “Road trip! Loaded the van & set off for IA. Met a great family when we stopped this afternoon. More to come” — along with a photo of a family and their baby.

Mrs. Clinton is traveling in the van, driven by a Secret Service agent, that takes her to work and events around New York. She is accompanied by a few aides.

On Tuesday, Mrs. Clinton will talk with students and educators at a round-table discussion in Monticello, Iowa, followed by a Wednesday discussion with small business owners in Norwalk, Iowa.