BOSTON — Red Sox left fielder Jason Bay married an American, has two American daughters and makes his living playing America's pastime.

Now he can say he's an American, too.

The 30-year-old from Trail, British Columbia, was among 360 people to become U.S. citizens yesterday in a naturalization ceremony at Faneuil Hall.

Dressed in a suit, Bay blended into the diverse group of immigrants holding postcard-sized flags who took the oath administered by U.S. District Court Judge Leo Sorokin.

Bay joined two military men and about a dozen children of newly sworn-in citizens to lead the crowd in the Pledge of Allegiance. One little boy donned a special Red Sox T-shirt with Bay's No. 44 decorated with red and white stripes and blue and white stars.

"I already knew it but I wanted to make sure I didn't mess it up in front of all those people," Bay said, admitting some jitters. "I didn't want the kids to upstage me."

Bay is the first Red Sox player to be naturalized since Dominican Republic-born David Ortiz was sworn in last summer.

"He gave me a little bit of what to expect," Bay said.

Like the Red Sox designated hitter, the new American citizen is still proud of his heritage from across the border.

"I don't denounce being Canadian at any point, but I'm definitely proud to be an American," Bay said.

Bay, who is batting .262, came to Boston from the Pittsburgh Pirates last season. He was leading the American League outfield All-Start balloting entering yesterday, the last day voting was open.

He was joined by his wife, Kristen, at the ceremony.

"Obviously it's something a lot of people dream of and my wife and both my girls are Americans, so it's a pretty proud day for me," Bay said.