GREENVILLE, Miss. -- Sen. Barack Obama won last night's Mississippi primary, the last Democratic primary for six weeks before what is expected to be a closely fought race in Pennsylvania April 22.

Sen. Obama's win last night was never really in doubt in a state where African-Americans account for one-third of the voters and about half of the Democratic electorate. The real question was whether the Mississippi win would yield a significant gain in the delegate count. While Sen. Hillary Clinton and her husband made several stops...