According to the 2010 census, the population was 17,339, an increase of 0.6% from 17,241 in 2000. It has a population density of about . The county contains six incorporated towns and many unincorporated communities. It is divided into 13 townships which provide local services.
Two U.S. Routes and five state highways pass through or into the county, along with one major railroad line.
This area had been occupied for thousands of years by succeeding cultures of indigenous peoples. The first European settlement of the western area of Indiana along the Wabash River was by French-Canadian colonists, who founded Vincennes in 1703.
After the Seven Years War, France ceded its territory in North America to Great Britain. In turn, after the American Revolutionary War, the Crown ceded this territory east of the Mississippi River to the new United States, including land it did not control, which was occupied by Native American nations.
In 1811 the Shawnee chief Tecumseh rallied several tribes to try to expel the European-American settlers from the area. When General William Henry Harrison took an army from Vincennes to the Battle of Tippecanoe in late 1811 to fight with the Indians, Zachariah Cicott served as a scout. Cicott had traded with Indians up and down the Wabash River, starting around 1801. The trail taken by Harrison's army, on its way to and from the battle site in Tippecanoe County, passed through the area that later became Parke County. The settlement of Armiesburg in Wabash Township was so named because Harrison and his army crossed the Raccoon Creek and camped near there on their way to the battle.
Formed on January 9, 1821 from a portion of Vigo County, Parke County was formed by an act approved by the state legislature. It was named for Captain Benjamin Parke, who commanded a troop of light Dragoons at the Battle of Tippecanoe. Parke was elected as a delegate of Indiana Territory to the U.S. Congress. In 1821, he was appointed as U.S. District Judge for Indiana.
First located at Roseville, the county seat was relocated to Armiesburg. In 1822, the county settled on Rockville as the permanent location. The state act had called for construction of county buildings to start within one year of the county's formation; but in the event, it did not start until 1824. The first courthouse was completed on the Rockville town square in 1826. The log structure doubled as a church.
In 1832 the log building was replaced by a brick structure, which served for more than 40 years until 1879, when it was demolisted for replacement by a new stone courthouse. The architects for this building were Thomas J. Tolan and his son Brentwood of Fort Wayne; they designed seven Indiana courthouses, as well as several in Ohio, Iowa, Illinois and Tennessee.
Construction of the courthouse at Rockville was completed in 1882 at a cost of about $79,000. Items deposited in the cornerstone included documents of the town's history, postage stamps, several varieties of grain grown in the county, coins, and photographs. A dedication ceremony took place on February 22, 1882, the anniversary of George Washington's birthday. The clock and bell were added later at a cost of about $1,500.
The Wabash and Erie Canal was completed through the area around 1850 and ran through Parke County on the east side of the Wabash River. It served several communities along the banks of the river until it was discontinued in the 1870s.