Upvote:4
The ten-pointed star on the lapel, and cap form makes this image readily identifiable to anyone familiar with the American Legion organization.
The three digit number indicates the 'Post' the individual belonged to, with this one indicating a connection to Johnston, Polk County, Iowa (part of Des Moines metro area). Not enough detail at this resolution to pick out what the smaller pins on the cap may represent.
Though eligibility requirement for membership indicates this individual served in the military, it does not indicate which branch of service.