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UK police forces used to be organised at the town level ( according to a close colleague who's the son of a retired police sergeant) but they changed after the Victorian era.
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Where I live, the old police station, which dated back to 1913, has the county police name engraved into the stonework. It was a county force with jurisdiction over the shire, with its own Chief Constable. The local large town had its own "burgh" police force. If the local regional councils merged, so would the local police forces.
In the mid 1950s a central police college was opened, it ids where all Scottish police officers went to be trained, no matter which force they were in.
In the 1970s, the numerous Scottish police forces were reorganised along with the new regions; Grampian, Lothian and Borders, Strathclyde, Fife etc. They all became county forces, with the counties being made of groups of the original shires and burghs. The smallest was still a police force of just over 500 officers.
A few years back, they all merged to make Police Scotland. One force covers the whole country. The cost savings have been huge, for example, instead of about 40 control rooms, there are now only 3 or 4.
If the history of policing in Scotland shows the USA anything, it is how important merging training was and that all officers should benefit from centralised, quality training.