According to the United States Census Bureau, the city has a total area of 3.3 square miles (8.5 km²), all of it land.
There were 305 households out of which 34.4% had children under the age of 18 living with them, 56.1% were married couples living together, 9.5% had a female householder with no husband present, and 31.5% were non-families. 27.5% of all households were made up of individuals and 13.8% had someone living alone who was 65 years of age or older. The average household size was 2.50 and the average family size was 3.07.
In the city the population was spread out with 27.3% under the age of 18, 9.6% from 18 to 24, 26.9% from 25 to 44, 21.4% from 45 to 64, and 14.8% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 96.4 males. For every 100 females age 18 and over, there were 89.7 males.
The median income for a household in the city was $25,625, and the median income for a family was $32,188. Males had a median income of $22,330 versus $16,250 for females. The per capita income for the city was $13,626. About 10.0% of families and 14.9% of the population were below the poverty line, including 17.8% of those under age 18 and 17.9% of those age 65 or over.
Amity was founded in 1847 by several pioneer families under the leadership of Deacon William F. Browning, who served as the Clark County surveyor during the years of 1846 through 1854. The group settled along the Caddo River, drawn to the area by an abundance of rich bottomland and fresh water. Browning constructed a two story log house just west of a small creek called Caney Creek, which soon became the center of the expanding community. It was Browning who gave Amity its name.
Together with other citizens, Browning formed the Bethel Missionary Baptist Church, the first religious organization in the area. They built a large log house that would serve as both the church and the school house. The first school teacher was Captain Robert S. Burke, a former military officer and Browning's brother-in-law. A few months later, the first Amity Post Office was established nearby.
With the outbreak of the American Civil War, the community saw dark times. Initially in support of the Confederacy, soon the community became divided, with the men of Amity leaving to fight in both the Confederate Army and the Union Army. In several cases, families were split by their loyalties, causing turmoil within the small community. Midway through the war, Union soldiers burned the Burke schoolhouse and the Browning cotton press.
Following the war's end, the center of the community shifted to the south side of the Caddo River, first settled by John Hays Allen and Dr. Amariah Biggs. Dr. Biggs was widely known as a physician and Methodist minister, and first settled in the area around 1850. The Amity Post Office was soon after relocated to this area. In 1870, retired army Colonel Philander Curtis, a Connecticut native, settled in the area. Curtis built the first house where the town of Amity now stands, and served for several years as the towns postmaster. In 1871, Col. Curtis, and businessmen Riley Thompson and Jacob H. Lightsey purchased property from John Hays Allen, and on that property they laid out plans for the town, centering around a public square. By 1874 Amity had become a thriving village, with several new businesses and churches. In 1877 an adjacent area became "Amity Township", and in 1880 the town made a move to become incorporated, but it did not come to pass until years later.
In the late 1870s a new schoolhouse was built. Its first teacher was Richard Melancthon Burke, son of Captain Robert Burke. The residents also formed the Amity Male and Female Academy, which eventually became Amity High School. Richard Burke died in 1883, and the school struggled until 1888, when Samual M. Samson arrived in Amity. Samson spent the next twenty years as the head of the high school, which at that time was a private school. After his departure, it was absorbed into the Amity Public School System.
In 1887, a false rumor that gold had been discovered in an area then known as the Trap Mountains resulted in a brief gold rush, which ended when the rumor proved false. Shortly after 1900, the Gurdon and Fort Smith Railroad was constructed through Amity, greatly improving the economy of the town. Soon, the logging industry began to thrive, with large sawmills opening in Rosboro and Glenwood. Amity became a main shipping and trade center for the area, and in 1905 the Bank of Amity opened, which now is on the National Register of Historic Places. In 1899 the town's first newspaper, the Amity Enterprise, went into circulation, followed by the Four-County Courier in 1915 and the Amity Owl in 1922. Just before World War II, the shortage of cinnabar caused a brief but productive mining industry in the nearby mountains south of the town, a phenomenon which became known as the Quicksilver Rush. However, any significant mining had ended by 1940, and following the war and an increased worldwide supply, the mines closed.
Logging soon became the main source of employment for the area, with the Bean Lumber Company opening in 1940, followed shortly thereafter by the Barksdale Lumber Company, both of which thrived through the 1980s. At its peak, the Bean Lumber Company was producing more than 150 million board feet of pine lumber and 120 million board feet of treated lumber annually, making it one of the largest distributors of southern pine in the United States. The Bean Lumber Company would later open mills in Glenwood, and in Buckner, Missouri.
By 2007 Bean Lumber was struggling financially, and was under investigation for financial matters. The Amity mill closed with no anticipation of it reopening, and the gates at the Glenwood mill were secured by Wells Fargo due to unpaid debt. All of these events thoroughly affected the local economy, diminishing employment opportunities in the community, as well as diminishing the population of the town, with many people being forced to search for work elsewhere.
In 1995 the Amity Public Schools consolidated with Glenwood to create Center Point High School, located midway between the two towns in Rosboro, Arkansas, in Pike County, Arkansas. The private Ouachita Hills Academy, associated with the Seventh Day Adventist Church, is still located in Amity.