Welcome to Plymouth Indiana Located on the Banks of the Yellow River. The newly elected Mayor of Plymouth is Mark Senter. In the year 2000 Plymouth had a population of about 10,000 residents. Plymouth is a small town with the large town convience. Every year the town of Plymouth holds its annual Labor Day Blueberry festival. The Blueberry fesitval is the largest festival in the state of Indiana. Over 500,000 people attend the festival over Labor day weekend . It is fun for all ages. The Blueberry festival includes live music, large parade, running events,tractor pull, softball tournament, basketball tournaments, hot air ballon launches and show., car show, and what I think are the best firework display.