Hours before the Padres faced the Braves at PETCO Park, Hairston said he couldn't wait to pull it on, and not just because he gets a little nostalgic at the sight of throwback uniforms.
"It carries a lot of weight for me and my family today," Hairston said.
Hairston was talking more about the number on the back of the jersey -- No. 42 -- than he was about the style of the jersey itself.
On Thursday, Major League Baseball celebrated Jackie Robinson Day as players, coaches and umpires wore the No. 42.
Introduced in 2004, Jackie Robinson Day was created to honor the continuing impact of Robinson and his legacy as the first African-American player to break the Major League color barrier.
Robinson is certainly an important figure for the Hairstons, who are African-Americans.
Their grandfather, Sam Hairston, played in the Negro Leagues, eventually becoming the first African-American to play for the White Sox in 1951, but only after Robinson paved the way four years earlier.
"It's a great day. It goes to show how Major League Baseball views Jackie Robinson and the meaning of this day," Hairston Jr. said. "If Jackie had failed, who knows what would have happened. Even Martin Luther King said Jackie Robinson spurred the civil rights movement."
Robinson played his first Major League game at Ebbets Field on April 15, 1947, as a member of the Brooklyn Dodgers.
In 1997, in honor of the 50th anniversary of Robinson's debut, his uniform number 42 was retired throughout the Major Leagues.
Robinson's memory lives on today in initiatives such as the Jackie Robinson Foundation, which was founded by his widow, Rachel Robinson, in 1973 to provide education and leadership development opportunities for minority students with strong capabilities but limited financial resources.
Atlanta rookie outfielder Jason Heyward, who is 20, has already gained a great sense of appreciation for what Robinson went through to get to the Major Leagues.
"Growing up, it's something I learned about when I was like 5 or 6 years old. Then when I became a teenager, I recognized that it was a big part of the civil rights movement," Heyward said.
"It's better by far because a lot of people sacrificed for us to be here today. I'm not saying that [racism] isn't all the way removed, but it's definitely come a long way. You have to be appreciative of that. It wasn't always easy for him."
That's something Hairston pondered Thursday.
"I remember someone a couple of years ago told me that we're the last descendants of the Negro Leagues," he said. "We're very proud of what my grandfather did. Without Jackie Robinson, none of it could have been possible. I'm so proud to wear No. 42 today."
Corey Brock is a reporter for MLB.com. Mark Bowman, a reporter for MLB.com, contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.