Our library is organized by subject, using the Library of Congress Classification system. African American history is a broad subject, meaning you may find relevant books through the library. However, two call number ranges that may be particularly helpful are:
E11-E143 America
E75-E99 Native Americans
E101-E135 Discovery of America
E151-E889 United States
E184-E185 African American History
E186-E199 Colonial History
E201-E298 Revolution
E441-E453 Slavery
F1-F975 State & Local history
F221-F235 Virginia
When searching a database of books (think: OneSearch, Google Books, or WorldCat):
Also, look for Library of Congress Subject Headings with those terms. A few useful subject headings for this project:
United States -- History -- Sources
United States -- History -- Colonial period, ca. 1600-1775 -- Sources
United States -- History -- Revolution, 1775-1783 -- Sources​