There are plenty of single american sisters out there, especially in the african american community. In fact, the recent rumblings in the muslim blogosphere is about how african american brothers are going over to morocco to marry, leaving all the sisters with no one.

Also, have you looked on any marriage sites? I know there are usually more brothers on there than sisters, but many of the brothers are oversees, and many american sisters won't marry anyone if it means sponsoring them for a green card. So, you would look a lot more appealing than a lot of the guys on there.