World Bulletin / News Desk
Some stores closed as early as 2:00 p.m., while others shut down around 2:30 p.m. EST (1830 GMT), and are to remain closed until 5.30 a.m. EST (0900 GMT) on Wednesday.
"At Starbucks we are proud to be a third place -- a place between home and work where everyone is welcome. A place where everyone feels that they belong," read a statement posted on stores' doors.
"We are sharing our ideas about how to make Starbucks even more welcoming," it added.
The racial-bias education in the company comes in the wake of two black men being arrested on April 12 at a Starbucks in Philadelphia.
The men asked to use the restroom, but a Starbucks employee refused to grant them access as they had not purchased anything, and eventually asked them to leave before calling police.
The men were arrested on suspicion of trespassing, but prosecutors have declined to pursue the charges due to a lack of evidence.
Starbucks CEO Kevin Johnson announced on April 17 that stores across the U.S. would close for training "geared toward preventing discrimination in our stores."
Starbucks shares in the U.S. were down 1.4 percent for the day at 2:30 p.m. EST (1830 GMT) Tuesday, erasing around $1.1 billion of its market value.