Los Angeles Angels at Texas Rangers

The teams wore 1972 throwbacks in honor of the Rangers' 40th anniversary season of the move from Washington.

Oakland Athletics at Boston Red Sox

A's and Red Sox wore 1936 uniforms to continue the 100th year of Fenway Park celebrations and honor the years the teams traded Jimmie Foxx.

New York Yankees at Boston Red Sox

On the 100th Anniversary of the opening of Fenway Park, the Red Sox and the Yankees (nee Highlanders) dressed in 1912 uniforms, complete with N#OB.

Iowa Cubs vs. Albuquerque Isotopes

The Iowa Cubs wore throwback Iowa Oaks uniforms for their game against the Albuquerque Isotopes, who dressed as the Albuquerque Dukes.

Source: twitter @IowaCubs

Source: Iowa Cubs' facebook page

Atlanta Braves at Houston Astros

On the 50th anniversary of their first game ever, the Houston Astros wore throwback uniforms from the 1962 Colt 45s.

Announced: Chicago Cubs at San Francisco Giants (June 2, 2012)

From #SFGiants twitter feed:

#SFGiants vs #Cubs on June 2nd featuring these 1912 Jerseys http://pic.twitter.com/YbotIP5l

San Diego Padres at Arizona Diamondbacks

The Diamondbacks celebrated their first ever "Throwback Game" as they celebrated the 10th Anniversary of the team's 2001 World Series Championship, leaving the Colorado Rockies as the only MLB team to have never donned a throwback uniform.