The area has been inhabited since the Stone Age, and was a centre of ironworking in Roman times. Crawley developed slowly as a market town from the 13th century, serving the surrounding villages in the Weald. Its location on the main road from London to Brighton brought passing trade, which encouraged the development of coaching inns. A rail link to London opened in 1841.
Gatwick Airport, nowadays one of Britain's busiest international airports, opened on the edge of the town in the 1940s, encouraging commercial and industrial growth. After the Second World War, the British Government planned to move large numbers of people and jobs out of London and into new towns around South East England. The New Towns Act 1946 designated Crawley as the site of one of these. A master plan was developed for the establishment of new residential, commercial, industrial and civic areas, and rapid development greatly increased the size and population of the town over a few decades.
The town contains 13 residential neighbourhoods radiating out from the core of the old market town, and separated by main roads and railway lines. The nearby communities of Ifield, Pound Hill and Three Bridges were absorbed into the new town at various stages in its development. In 2009, expansion was being planned in the west and north-west of the town, in cooperation with Horsham District Council. Economically, the town has developed into the main centre of industry and employment between London and the south coast. Its large industrial area supports manufacturing and service companies, many of them connected with the airport. The commercial and retail sectors continue to expand.
The area may have been settled during the Mesolithic period: locally manufactured flints of the Horsham Culture type have been found to the southwest of the town. Tools and burial mounds from the Neolithic period, and burial mounds and a sword from the Bronze Age, have also been discovered. Crawley is on the western edge of the High Weald, which produced iron for more than 2,000 years from the Iron Age onwards. Goffs Park—now a recreational area in the south of the town—was the site of two late Iron Age furnaces. Ironworking and mineral extraction continued throughout Roman times, particularly in the Broadfield area where many furnaces were built.
In the 5th century, Saxon settlers named the area Crow's Leah—meaning a crow-infested clearing, or Crow's Wood. This name evolved over time, and the present spelling appeared by the early 14th century. By this time, nearby settlements were more established: the Saxon church at Worth, for example, dates from between 950 and 1050 AD.