Vintage Cars: seatbelts, ford mercury, cars ford

Question
What was the first american car to have seatbelts? Was it the 1956 Ford?

Was the world's first a Mercedes?

Answer
Actually, a tough question.  Ford was the first to offer seat belts as an option in its full line of cars (Ford, Mercury and Lincoln), but they may have been available on individual models from other makers (or installed by dealers) before that.  Volvo claims to be the first to offer seat belts standard on their models, in 1959.  They were also the first to offer a 3-point harness, which in my book was the most important advancement in seat belts.