Diego Estrada started his first half marathon a bit slow. He ended it with the American flag on his shoulders.

After pulling away late to win the U.S. title with a time of 1 hour, 51 seconds in his debut at the distance, Estrada couldn't keep his patriotism down.

"I am an immigrant," Estrada said. "I was 13 months when I immigrated to this country. I became a citizen in 2011, so for me to win a U.S. championship, it means more to me than any other runner."

Defending champion Meb Keflezighi, who, like Estrada, became a U.S. citizen in his early 20s, finished fourth.

Kim Conley won the women's title in 1 hour 9 minutes and 44 seconds. She began to pull away from the pack around the 10-mile mark and grew her lead to 22 seconds over Brianne Nelson by the 12-mile mark. Conley, the 2014 American champion in the 10,000 meters, won her first half marathon championship. Nelson finished second 32 seconds behind Conley.

Estrada who found himself in the pack early, pulled away around the four-mile mark and grew the lead to 20 seconds over Matthew Llano and Jared Ward by the halfway point of the race.

"Based on training, when we first started, our goal was to run 63:20," Estrada said. "I called my coach and said I was not going to train this hard to run 63, I wanted to run under 61. He said these were the paces I had to run, so I got up to a 10-mile tempo at a 4:35 pace."

That translates to a time of 60:05.

"I knew I could do it, but I didn't know about the extra miles. When we went out at a slower pace, I decided to take over and do a tempo. I knew I could run that time, but I didn't know if I could get to the finish."

He did with plenty of room to spare, raising his arms as he broke the tape with no one else in sight. Estrada finished ahead of Ward by 51 seconds.

"You dream of being a US champion, it doesn't matter the distance," Estrada said. "You are holding that flag and your main concern is not to let that flag touch the ground because I have so much respect for it."

"My parents have worked so hard to bring me here and give me the opportunity to be able to raise that flag. I feel like it is a message to my family that the sacrifice was worth it. I'm an American. I'm a Mexican-American, but this is my home, and I'm going to represent my country."

Keflezighi, the current Boston Marathon titleholder, finished in 1:02:18 seconds.

"I thought 1:01 to 1:02 was going to be good enough to win, but Estrada just ran a phenomenal race," Keflezighi said. "I saw the pace, and thought maybe there was room for him to make a mistake and tried to close the gap. Once I got past seven miles, I knew he was going to have a day and not going to be able to close the gap."