The Ford Explorer is a full-size crossover SUV sold in North America and built by the Ford Motor Company since 1990, as a replacement for the smaller but related Ford Bronco II. It is manufactured in Chicago, Illinois (it was also assembled in Hazelwood, Missouri until the plant closed on March 10, 2006). The Ford Explorer was instrumental in turning the SUV from a special-interest vehicle into one of the most popular vehicle types on the road. It is marked as Ford's only mid-sized SUV and is slotted between the larger Ford Expedition and the smaller Ford Escape. Though the Ford Escape is a crossover and the Expedition and Explorer are traditional SUVs, Ford considers all three vehicles to make up their "SUV" portfolio. Their "crossover" portfolio consists of the Ford Flex and the Ford Edge.
The Explorer has also been involved in controversy, after a spate of fatal rollover accidents involving Explorers fitted with Firestone tires. Both two-door Explorer Sport and four-door models of Explorer have been sold. Part-time four-wheel drive is an available option, and since 1995 this has been a 'shift on the fly' system with full protection against being engaged at high speed. A specially modified Special Service Vehicle version is also available from Ford Fleet for law enforcement agencies, fire departments, and EMS agencies. Explorer was also the name of a trim package offered on the Ford F-Series trucks from 1968 to 1986. The 2011 Ford Explorer was named North American Truck of the Year.