Ahh yes, that would be called "Top Thrill Dragster". It's located at Cedar Point Amusement Park in Sandusky, Ohio. At the time it opened, I believe it was considered the World's Tallest at 420 feet.
The riders sit in a dragster-type car. Riders go from 0-120 miles per hour in under 4 seconds at the start. It's a 90 degree ride to reach the top of the coaster, then you corkscrew 270 degrees around back to earth. It's a great ride! But beware - the coaster is designed to go juuuuuust fast enough to go over the top - sometimes it doesn't make it, and riders are pulled backwards by gravity to the starting line! (That's never happened to me, but I've seen it happen! There are electromagnetic brakes that shoot up from the track after the train takes off to catch it just in case it rolls back! It sounds like rapid gunfire when they go up!)
It used to be faster. It had a radar gun on the cars when it opened in 2003. It would consistently go 140MPH or more (yes, still in under 4 seconds), but the propulsion system would frequently break down. So they "slowed" it down in successive years to make it more reliable. The ridership in Year 1 was about 500,000 - sucessive years it has been about 1,000,000+ due to the increased reliability.
The amusement park is about an hour from my home. I used to get season passes, but haven't for a few years.
Cedar Point has 17 great roller coasters, and is consistently ranked as one of the best amusement parks in the world. I'd be happy to host anyone who wants to go! It's worth the trip!