The steepest: Baldwin Street
A bit of an argument rages on this one — folks get pretty territorial — but it all comes (rolls?) down between the United States and New Zealand. Baldwin Street in Dunedin, New Zealand (left), runs for more than 1,000 feet, much of it at an incline of 35 percent. Canton Avenue in Pittsburgh, Pennsylvania, has an incline of 37 percent — but for only a few feet.
Regardless of which street you're on, if you're parking, turn the wheels into the curb. And set the emergency brake.