Comment by corebit

Keeping the peace was a concept in both countries when they split and was the duty of the sheriff which still exists in both countries and is actually still very functional in the US. That some localities with very large populations evolved an even more local office for keeping the peace is entirely consistent with the evolution of police tracing back to England before it existed as a modern concept. The simple fact is that slave patrols just did not morph into the general-purpose peace keeping organizations that today we call police.