The Bureau of Justice Statistics (BJS) reports on department sizes, but it only includes the fifty largest departments. I do not believe the fifty largest departments are representative of smaller departments, as most, if not all, of the cities would have a large presence of non-resident employees and tourists compared to smaller cities (a possible justification for more sworn officers).
As of January 1, 2013, the more than 12,000 local police departments in the United States employed an estimated 605,000 persons on a full-time basis. This total included about 477,000 sworn officers (those with general arrest powers) and about 128,000 nonsworn employees. (source)
According to the Census, the US population was 315,035,869 on January 1, 2013. The math would mean there is 1 officer for every 660 citizens on average.
With the national conversation #DefundThePolice, I was hoping to find data on individual departments that are not in the top fifty. I would like to know the amount of sworn officers per population in individual municipalities.