Memorial Day is the unofficial start to summer road tripping.  With the price of gasoline creeping down, AAA projects that 34.8 million Americans will be traveling 50 miles or more from home during the holiday weekend, up1.2 percent from last year.

Planning a road trip can be a science.  Should you stick to the highways or take the smaller back roads?  Does leaving early work, or is it better to drive through the night?  Factoring in pit stops is all part of the calculation.   

For anyone who's driven the country's busiest highways, like I-95 between New York to Washington, you know that picking the right place to stop means more than having toilet paper in the bathroom stall.  Some highway rest stops are so crowded just parking can be a challenge and wait for food lines can be longer than those at the toll booths.

USA Today asked foursquare, the mobile app that lets travelers "check in" at venues around the world, for a list of the rest stops with the most check-ins last Memorial Day weekend --in other words places to avoid like the plague. 

Here's the top ten:

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- Delaware Welcome Center Travel Plaza (Newark, Del.)

- Maryland House Travel Plaza (Aberdeen, Md.)

- Molly Pitcher Service Area (Cranbury, N.J.)

- Lake Forest Oasis (Lake Forest, Ill.)

- Cheesequake Rest Area (Sayreville, N.J.)

- Woodrow Wilson Service Area (Hamilton, N.J.)

- Chesapeake House Service Plaza (North East, Md.)

- Grover Cleveland Service Area (Woodbridge, N.J.)

- Charlton Service Plaza (Charlton, Mass.)

- Des Plaines Oasis (Des Plaines, Ill.)