Clark County Post Offices

100 W Alabama Ave
Casey, Illinois 62420

115 N 7th St
Marshall, Illinois 62441

2 N York St
Martinsville, Illinois 62442

211 W Union St
West Union, Illinois 62477

21962 N 1470th St
West York, Illinois 62478

130 W State St
Westfield, Illinois 62474

Clark County

There are 6 US Post Offices in Clark County serving a total of 16,767 residents equating to 2,795 residents per post office. It's estimated that approximately 26,762 packages are handled across the 6 county post offices annually. Clark County is a county located in the southeastern part of U.S. state of Illinois, along the Indiana state line. As of the 2010 census, the population was 16,335. Its county seat is Marshall. The county was named for George Rogers Clark, an officer who served in the American Revolution.