The town is an unparished borough in the northern part of Sussex, bordering Surrey. The borough is bordered by the Sussex Local Authorities of Mid Sussex and Horsham Districts, and by the Surrey authorities of Mole Valley and Tandridge Districts, and the Borough of Reigate & Banstead. The town is a two-tier area, also coming under the remit of West Sussex County Council
The area developed to a small-sized town of under 10,000 people until the World War II. In 1947, it was designated as a New Town area under the New Towns Act of 1946. Its development then ballooned during the 1950s and 1960s, bringing it to a population of around 60,000. Since that time, the town has continued to grow around its neighbourhood structure (and now conists of 13 neighbourhoods. A large influence on the town's develoment has been the airport at nearby London Gatwick Airport, which is contained within the borough's boundaries. The airport is now the busiest single-runway airport in the World, and the sixth busiest overall.