This part is a later time frame:

EXCERPT

http://www.slmpd.org/history/index.htm

The Civil War brought about many changes to Saint Louis, including its police Department. By 1866, the city had a population of 204,000. That year the Department increased in size to 225 officers, whose duty it was to patrol the 16 square miles of territory. One of the major problems facing the Department was the task of capturing steamboat criminals. The city had become a major center in river traffic and various gangs of men joined forces and committed crimes of piracy along the levee. This problem became so widespread that the Department had to initiate a steamboat detective squad. Each steamboat captain would pay to the Department the sum of $1.00 per day. In return, an officer would be assigned to the ship while it was docked. From all accounts, this plan worked well in reducing the number of crimes on the steamboats.

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