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You can usually see the claws on raccoon tracks. Their front feet are between 1 and 2.5 inches in width and length, but their back feet are a bit longer (up to 4 inches long).
Raccoons typically walk by grouping their right and left paws together, so when you see the tracks you will find a long string of groups of two tracks at a time. Raccoons can be found in the woods but they also like to hang out near people and their trash.
Virginia opossums have claws, but their claws don't always show up on their tracks. Their front feet are roughly 2 inches wide and only 1.5-2 inches long. This is unusual: their front feet are wider than they are long. Their back feet are roughly 2-2.5 inches long and wide. They are also unique because the 'thumb' on the back feet is separated from the rest of the toes.
When possums walk they bring their back left back foot up to their left front foot and then their right back foot up to their right front foot. So, when you see their tracks, there will be several groupings of a single front foot and back foot together.
Striped skunks have five toes on their front and back feet, but they might only show four toes because the fifth toe is much smaller. You will usually be able to see claw marks on their tracks.
Their front tracks are about 1.5 inches long and 1.25 inches wide. Their back feet are also 1.25 inches wide and even longer (1.7 inches). You may find a fairly wide footpad. You will most likely see that all the toes are in the front (none are sticking out to the side).
Another sure way to tell if a skunk has been around is its smell!