In may, 1917, the u. s. army opened ft. jackson on the edge of columbia, south carolina, in order to

The correct answer is train soldiers to fight in WWI

Although the United States did not want to participate in the war at first, it soon became clear that they would have to step in. however, they lacked the necessary amount of soldiers so they started training new ones for this endeavor. Fort Jackson, as well as numerous other training places, was opened and the training began.

Prepare for World War I.

Explanation:
Ft. Jackson was used to recruit and train men for World War I.
The location of the fort was to help recruit African American men for the war since this was a first opportunity, for most, to fight for the US since obtaining citizenship.