In 1894, Westbury parish was reduced in size when a new civil parish of Dilton Marsh was created from its western part (all the land west of the Biss), and likewise Bratton parish from its eastern part. A further reduction in the north created Heywood parish in 1896. Westbury Urban District was formed in 1899, with the same boundaries as the parish. It was abolished in 1974 as a result of the Local Government Act 1972, its area becoming part of West Wiltshire district. The district was in turn abolished in 2009 on the establishment of Wiltshire Council as a unitary authority.