Flyingfisher:
Here's a possible workaround:
1. Draw a rectangle, fill with black, and send it behind the existing tiff; It should be a little larger than the tiff;
2. Select the tiff and the rectangle, go to the transparency palette, and from the flyout choose "Make Opacity Mask"; You should now have the white portion of the art showing in black, and nothing else;
3. Object>Rasterize;
4. From the appearance palette flyout, choose "Add New Stroke";
5. Effect>Path>Outline Object;
6. Object>Expand appearance, then select only the raster portion and throw it out.
You should now have a useable, but not clean, vector path. It's not perfect, but it's better than nothing.
Or, you could make a path in Photoshop and bring it into Illustrator.
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