Counties (Detached Parts) Act 1844 in the context of Boundary commissions (United Kingdom)

The administrative boundaries of Worcestershire, England have been fluid for over 150 years since the first major changes in 1844. There were many detached parts of Worcestershire in the surrounding counties, and conversely there were islands of other counties within Worcestershire. The 1844 Counties (Detached Parts) Act began the process of eliminating these, but the process was not completed until 1966, when Dudley was absorbed into Staffordshire.

The expansion of Birmingham and the Black Country during and after the Industrial Revolution also altered the county map considerably. Local government commissions were set up to recommend changes to the local government structures, and as early as 1945 recommendations were made to merge Worcestershire with Herefordshire. Eventually in 1974, a form of this recommendation was carried out, most of Worcestershire was combined with Herefordshire to form a new county named Hereford and Worcester, while the northern Black Country towns and villages of Worcestershire, along with adjoining areas of Staffordshire and Warwickshire, formed the new administrative county of West Midlands.

Between the late 11th century and 1844, the English county of Shropshire (or Salop) possessed a large exclave within the present-day Black Country and surrounding area. This territory was gained from neighbouring Worcestershire, and the exclave's border corresponded with the medieval Manor of Hala (or Halas, Hales). Shropshire contained the townships of (what are now known as) Halesowen, Oldbury, Warley Salop, Ridgacre, Hunnington, Romsley and Langley. The exceptions were Cradley, Lutley and Warley Wigorn, which were exclaves or enclaves still aligned with the original county. Bounded entirely by Staffordshire and Worcestershire, Hala was part of Brimstree hundred, and totally detached from the rest of Shropshire. Bridgnorth, the nearest town within the main body of Shropshire, is 16.8 miles (27.03 km) away from Halesowen, whilst the county town of Shrewsbury is 34.6 miles (55.62 km) away.

In 1844, following enactment of the Counties (Detached Parts) Act 1844, these parts of Shropshire were reunited with Worcestershire and remained within that county until 1974. Halesowen and Oldbury are currently part of the West Midlands metropolitan county.