Cornwall County Constabulary establishment of 500 and an actual strength of 446. On 1 April 1967 it amalgamated with Devon and Exeter Police and Plymouth City Police to form Devon and Cornwall Constabulary. Cornwall County Constabulary Cornwall County Constabulary was the Home Office police force for the county of Cornwall, England, until 1967. The force was formed in 1857. It absorbed Bodmin Borough Police in 1866, Liskeard Borough Police in 1877, Launceston Borough Police in 1883, Falmouth Borough Police, Helston Borough Police, Penryn Borough Police and St Ives Borough Police in 1889, Truro City Police in 1921, and Penzance Borough Police and the
Cornwall, California became part of the Southern Pacific system in 1888). The coal railroad crossed the San Pablo and Tulare line using an overhead trestle. A post office operated at Cornwall Station from 1881 to 1888. Cornwall post office operated from 1890 to 1911. The Cornwall area, together with the nearby town of Black Diamond, was officially renamed "Pittsburg" on February 11, 1911, which may explain why the Cornwall Post Office stopped operations in that same year. Cornwall, California Cornwall, formerly known as Cornwall Station, was an unincorporated community in Contra Costa County, California, before it was absorbed into the City of