<P> Since its creation in the fifth century , Sussex has been subject to periodic reform of its local governance . After the Reform Act of 1832 Sussex was divided into the eastern division and the western division , these divisions were coterminous with the two archdeaconries of Chichester and Lewes. : ) In 1889 , following the Local Government Act 1888 , using those same boundaries , Sussex was divided into two administrative counties , East Sussex and West Sussex together with three self - governing county boroughs , Brighton , Eastbourne and Hastings . In 1974 , under the Local Government Act 1972 , the county boundaries were revised with the mid-Sussex area of East Grinstead , Haywards Heath , Burgess Hill and Hassocks being transferred from East Sussex into West Sussex along with Crawley and the Gatwick area that was formerly part of Surrey . The county boroughs were returned to the control of the two county councils but in 1997 the towns of Brighton and Hove were amalgamated as a unitary local authority and in 2000 , Brighton and Hove was given City status . Although it is administered as the two ceremonial counties of East and West Sussex , there continue to be a range of organisations that operate throughout the ancient borders of Sussex such as the Diocese of Chichester , Sussex Police , the Sussex Archaeological Society the Sussex History Society and the Sussex Wildlife Trust . </P>
when did sussex split into east and west
1889