Obama winning Southern states

I just made a post about Georgia, but Obama could win South Carolina, North Carolina, Virginia, and Mississippi too:

When 25% of a state's electorate is blacks who vote for Obama, he must win 33.34% of everybody else to win that state:
McCain: 49.995%
Obama: 50.005
Blacks for Obama (25%): 0%, 100%
Everybody else (75%): 66.66%, 33.34%

When 30% of a state's electorate is blacks who vote for Obama, he must win 29% of everybody else to win that state:
McCain: 49.7%
Obama: 50.3%
Blacks for Obama (30%): 0%, 100%
Everybody else (70%): 71%, 29%

When 35% of a state's electorate is blacks who vote for Obama, he must win 24% of everybody else to win that state:
McCain: 49.4%
Obama: 50.6%
Blacks for Obama (35%): 0%, 100%
Everybody else (65%): 76%, 24%

When 40% of a state's electorate is blacks who vote for Obama, he must win 16.67% of everybody else to win that state:
McCain: 49.998%
Obama: 50.002%
Blacks for Obama (40%): 0%, 100%
Everybody else (60%): 83.33%, 16.67%

I bet he needs 30% for Virginia, North Carolina, and Georgia, 35% for South Carolina, and 40% for Mississippi. Here's the 2004 statistics for these states (from CNN):

Virginia:
Bush: 54%
Kerry: 46%
Whites (72%): 68%, 32%
Blacks (21%): 12%, 87%
Latino (3%), Asian (2%), Other (2%): n/a

North Carolina:
Bush: 56%
Kerry: 41%
Whites (71%): 73%, 27%
Blacks (26%): 14%, 85%
Other (3%): n/a

South Carolina:
Bush: 58%
Kerry: 41%
White (67%): 78%, 22%
Black (30%): 15%, 85%
Other: 4%

Georgia:
Bush: 58%
Kerry: 41%
Whites (70%): 76%, 23%
Blacks (25%): 12%, 88%
Latinos (4%): 56%, 43%
Other (2%): n/a

Mississippi:
Bush: 60%
Kerry: 40%
Whites (65%): 85%, 14%
Blacks (34%): 10%, 90%
Other (1%): n/a