Here is a terrific old advertisement from 1918, soliciting young men between 22 and 35 to join the Metropolitan Police Department (a limited number of intelligent and educated women will also be considered).
Click on the advertisement for some greater details because it’s really interesting to read through this World War I era ad.
All persons between 22 and 35 years of age are eligible, except men in Class 1 under Selective Service Act.
The Police Department of the District of Columbia today offers an excellent opportunity for employment to men who are mentally and physically strong, who are alert and trustworthy, who may possess qualities of leadership, and who desire to enlist in one of the most important branches of public service., with healthful outdoor work, with a good salary to start, and opportunity for promotion.