When the big event was over, Tom and Kimberly Patterson strapped their two children in their truck and drove away from the White House back home to Huntingtown.

The youngsters, Kristina, 5, and Tommy, 3, knew little about the reason for Tuesday's ceremony--First Lady Hillary Clinton had tied a red ribbon on their Chevrolet Suburban--except it had something to do with their big sister who was no longer with them.

"I told my kids, 'We had to do this for your sissy,' " Kimberly Patterson said.

It was more than four years ago that the Pattersons had buckled two children into the back of another vehicle, a van, and headed off on another trip, that time to visit family in Garrett County in western Maryland. Their daughter, Mary Theresa, then 2, was along for that ride--her last.

"She was killed by a drunk driver," Kimberly Patterson said. "As we we were traveling along 219, the driver of the other vehicle crossed the yellow line and hit us broadside, and our truck spun I can't tell you how many times, and our daughter was thrown out of the vehicle. She landed in a ditch."

Today, Tom Patterson, who is 34 and a sales representative for a printing company, is vice president of the central Maryland chapter of Mothers Against Drunk Driving (MADD). He and his family were at the White House on Tuesday to take part in a ceremony commemorating MADD's ribbon campaign, "Tie One On for Safety," which encourages people to tie ribbons to their vehicles as a reminder to drive soberly, especially during the holiday season.

The campaign runs from Thanksgiving to New Year's Day, Patterson said.

"This a plea for people just to designate a driver," he said. "This is not a plea for people to stop drinking."

Patterson's plea is obviously a personal one, rooted in the accident that claimed his daughter's life. Patterson said that both of his daughters were strapped into their car seats, but the force of the collision blew out all the windows and "was so great it broke off the back seat from the van." Their oldest daughter was ejected from the vehicle.

"I always called her . . . sunshine girl," said her mother, 31, who is a legal secretary. "And her Daddy always used to call her 'girlfriend'. . . . she was the love of our life. She was in several beauty pageants and she basically got first place in every single pageant."

It was in the aftermath of the accident, while searching for Mary Theresa, that her father saw one of the two occupants of the other car. Patterson said he seemed "extremely drunk."

"I started yelling at him, 'See what you've done! See what you've done!' "

Although the driver ultimately was sent to prison, Patterson said he found it "sickening" that at the time vehicular homicide was still treated like a relatively minor offense. He also was angered by the fact that those convicted didn't serve out their full sentences and were eligible for parole so soon--like the man convicted in his daughter's case.

MADD representatives supported the family through the legal proceedings, helping them to "understand how trials and the court systems work," Patterson said.

Their continued support made him want to give back to the organization. "I'm the type of guy, if somebody helps me out I will help them out a thousand times in return. . . . I keep saying, 'If these people weren't here I'd be--I hate to say--in the loony bin or crazy house.' "

Tuesday's event was a way of giving back to MADD--and, of course, "out of respect for my daughter," Patterson said.

"It can happen to you. . . . I'm just doing my part because of what happened to us."