Four years ago, the Metro trip to the inauguration of Barack Obama was a giant party, a celebration of national unity and a homage to history.

This year, the feeling on the train is more business-like — still happy but not ebullient, determined but not ecstatic.

In one sense, the notion that the inauguration of an African American as president is perfectly normal and expected is a great victory for our country. This crowd is celebrating a vindication at the polls for what just four years ago seemed an impossible dream — if you will forgive that cliched reference from this old Red Sox fan.

(Related: See Tom Toles’s Inauguration Day cartoon.)

But don’t let anyone tell you that the commitment of four years ago is gone. In the middle of my Metro ride this morning, Natalie Kohlhaas sat next to me. She is here with her husband and three boys, ages 15, 14 and 10. Three days ago, her husband, Curtis, managed to get tickets. “On Saturday morning, we rented a car, loaded into it and road-tripped for 11 hours.”

“We’re Democrats,” she said, “but we also thought it was important for the boys to see how we peacefully transfer power — or, in this case when someone is re-elected. This does not happen everywhere, and we wanted them to see it.”

Curtis Kohlhaas went to the second Clinton-Gore inauguration when his wife was two weeks away from delivering their first child. “I came by myself,” he said, “but I was determined that she would get to come some day.”

So 16 years and three kids later, the Kohlhaas Family came to our celebration of freedom together.