As a history major and minority studies major... you need to know that certain groups in the United States may have detailed history dating back to 1800...those groups are African Americans and those of Spanish heritage and Asian and Native American heritage...for these groups documents are so limited...one site is
www.ancestry.com there are payment plans with this service...then there are the library of congress and your public library...contact your university or college departments of American or United States History and Minority studies... which includes the studies of Latin America and African American and Asian American studies for example (there are more) tell the professor what your objectives are and they will either help you... if there is a community element to that university or college department...you may have to pay for copies of papers in your search...and talk to older relatives