If you go to baseball-reference.com and look up Negro League teams, you can find team rosters that show place of birth.
Just for the 1940 Negro National League, I see Texans Homer Curry, Jesse Walker, Zolie Wright, Biz Mackey, Henry McHenry, and Roy Parnell. You'll need to go through each
team in each league year-by-year.
See
http://www.baseball-reference.com/nlb/league.cgi for a list of links to leagues.
Kevin