The previous record was held by Japan at only 366 MPH and without any rockets. The Air Force’s rocket sled crushes that record, at 633 MPH The sled could theoretically traverse the continental United States in about four hours.
With the flick of a spark the 846th Test Squadron’s magnetically levitated sled system or MagLev, broke a world record. Followed by a plume of smoke, the rocket-propelled sled zipped down the 2,100-foot track at 633 miles per hour.

https://www.youtube.com/watch?v=X-6SKGWW1J8&feature=youtu.be

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