African-American Migration to Muskogee County, OK

I am currently researching my family who migrated from Mississippi to Muskogee (Vann), OK shortly after WWI. There are three siblings, Chester Washington b. 1889, Scott Washington b. 1887 and Carrie (nee Washington) Gary b. 1885.

Chester Washington was married to a Leatha or  Leathan b. 1892 who was also born in Mississippi. the last known record is of him living in Muskogee as of 1955. Scott Washington apparently didn't marry, as far as the records indicate. Carrie Washington married Albert Gary and had the following children: Johna, Mary, Matlee, Julia, James and Ruth.

Because they migrated recently to the state, I'm a little unsure as to what records would be available to me concerning this family. Any records resources would be great. Thank you

The Family Griot