Possibly a relative or fellow educator. On the back is written the date, Sunday, March 26, 1899.
EDIT: I discovered that The Library of Congress holds a glass negative of this same portrait in their C. Bell / African Americans collection. On the negative she is identified as M. After some research I believe her full name was Mary Virginia Over, a public school teacher in D.She was born in 1879 in Washington, D. Married Willian Howison Lewis, Sr. Dimensions of the mount are 6" x 4.25". Visit my shop for more interesting images. See last image in this listing for info.
John wilkes broadway actor rare.