Prior to 1839, the United States government forcibly removed the Caddo Nation of Native Americans—longtime local inhabitants who had first settled the area over 1,000 years before Europeans' 16th-century arrival in mainland North America—from the area of Northern Louisiana that included the parcel that would later become the town of Plain Dealing. In 1839, George Oglethorpe Gilmer and his son, James Blair Gilmer, bought 5,000 acres of this land—now described as a "vast, unsettled wilderness"—from the United States government, calling a portion of this acreage "Plain Dealing" after the family's Virginia plantation. The "Plain Dealing" name became official when the town was formally chartered on April 24, 1890. Notable points of more recent history include the following:
Plain Dealing recorded the state's hottest temperature ever,, on August 10, 1936.
The Plain Dealing Post newspaper was established in the 1980s by publisher Danny D. Scott of nearby Springhill.
As of the census of 2000, there were 1,071 people, 418 households, and 280 families residing in the town. The population density was 673.0 people per square mile. There were 481 housing units at an average density of 302.2 per square mile. The racial makeup of the town was 55.28% White, 42.67% African American, 0.65% Native American, 0.09% Asian, and 1.31% from two or more races. Hispanic or Latino of any race were 0.47% of the population. There were 418 households out of which 32.1% had children under the age of 18 living with them, 43.1% were married couples living together, 20.1% had a female householder with no husband present, and 32.8% were non-families. 29.4% of all households were made up of individuals and 15.1% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.95. In the town, the population was spread out with 25.7% under the age of 18, 7.4% from 18 to 24, 22.8% from 25 to 44, 22.3% from 45 to 64, and 21.8% who were 65 years of age or older. The median age was 40 years. For every 100 females, there were 81.2 males. For every 100 females age 18 and over, there were 76.9 males. The median income for a household in the town was $24,706, and the median income for a family was $32,361. Males had a median income of $32,132 versus $25,455 for females. The per capita income for the town was $14,906. About 23.6% of families and 26.8% of the population were below the poverty line, including 34.9% of those under age 18 and 20.4% of those age 65 or over. In the years since the Louisiana State Legislature legalized riverboat casino gambling in 1991, the casino industry of nearby Shreveport has become a major source of employment for Plain Dealing residents, as Chris Redford, then a crime reporter with KTBS News in Shreveport, explained in a 2009 television documentary.
Mollie Burdett Banks Curry Gray, a Plain Dealing resident, was a great-great-grand-niece of George Washington. When she died in 1958 in Shreveport, she was listed as the oldest descendant of President Washington.
Robert Houston Curry, first husband of Mollie Gray, was from 1888 to 1892 a member of the Louisiana House of Representatives for Bossier Parish.
John J. Doles, a business man and politician, member of the Louisiana State Senate from 1952 to 1956, and president of the Louisiana Bankers Association from 1956 to 1957
John J. Doles, Jr., Plain Dealing banker and civic leader
