In the late 1800s, Martinsville's Main Street, part of the National Road, served as a corridor for commerce and community where area residents came to visit friends, exchange news, and trade cash and farm goods for supplies and services. Merchants along the road sold groceries, clothing, hats, candy, hardware, and other goods, while blacksmiths and other shopkeepers provided services. Early merchants often relied on barter and exchange to supplement cash transactions, with Clark County residents offering eggs, poultry, fruits, and vegetables in return for groceries, dry goods, and services, and any difference in value entered in customer accounts. Shops also extended credit, recording debts in ledgers until accounts were settled. In the early 1900s, Ohio Oil Company became Martinsville's largest employer, and from 1906 to 1908 it built 225 oil tanks on 1,200 acres west of town. That oil boom stimulated the local economy, drew many construction workers, and helped raise the town's population from 1,000 in 1900 to 1,500 in 1910.