County adjacent to Indianapolis-Marion County on the southwest and part of the Indianapolis Metropolitan Statistical Area. Settlers began entering land in the area that is now Morgan County in 1820. The county was organized in 1821, with Martinsville platted as the county seat in March, 1822. The northern part of the county, including the town of Mooresville (platted in 1824), was settled by Quakers. The county's first white settler, Asa Bales, a North Carolina Quaker, later founded the town of Westfield in Hamilton County (1834). Samuel Moore built an excellent grist mill on White lick Creek near Mooresville that contributed greatly to the towns development during the 1830s.

Through the 1830s Martinsville relied on the whiskey trade for much of its modest wealth and growth. By the mid-1830s there were eight distilleries producing corn and rye whiskey and apple and peach brandy and dozens of taverns in and around Martinsville. After 1835, however, the economic focus switched to the pork trade. Hogs were driven from all over central Indiana to slaughterhouses at Martinsville. The carcasses were packed during the winter and floated on flatboats down the West Fork of White River to the Ohio River, arriving in New Orleans by the spring. This trade system flourished until the development of railroads in Indiana after 1850.

In 1853 the Martinsville and Franklin Flatbar Railroad was completed to Martinsville, but operated for less than five years. The completion of the Indianapolis and Vincennes Railroad in the late 1850s spurred growth in the county seat. The pork packing and shipping business continued to flourish, and the town added a large woolen factory: The completion of the Indianapolis and Vincennes Railroad to Mooresville in 1867 spurred the pork shipping industry as farmers took advantage of the large stock pens just south of town while waiting for trains. An INTERURBAN line constructed to Mooresville in 1901 and hourly trains into Indianapolis gave residents easy access to the capital city's shops and department stores. By 1903 the interurban line extended to Martinsville. Speed and convenience made the interurban the top choice for both freight and passenger service, and the Indianapolis and Vincennes Railroad was all but abandoned by 1920.

By the 1930s Morgan County fanners were using trucks to haul their produce to market and cars for personal travel. With the railroad used sparingly and the interurban abandoned, business slowed in the county's two largest towns. Today Morgan County is a predominately rural area with a population of almost 56,000 (1990). Agriculture is an important economic factor in the county, but more residents in and around Martinsville and Mooresville work in factories and offices than farm. Martinsville, the county's only city, had a population of 11,677 in 1990, while Mooresville had 5,541 residents.