1920 Olympic Champion Charlie Paddock was born in Gainesville, as were exotic animal trapper Frank Buck and Country music singer and poet Red Steagall. Air Force Chief of Staff Lew Allen graduated from high school in Gainesville. Atlanta Falcons football player Kevin Mathis graduated from Gainesville High School in 1992.
According to the United States Census Bureau, the city has a total area of 17.0 square miles (44.1 km²), of which, 17.0 square miles (44.0 km²) of it is land and 0.04 square miles (0.1 km²) of it (0.18%) is water.
There were 5,969 households out of which 33.2% had children under the age of 18 living with them, 49.2% were married couples living together, 13.9% had a female householder with no husband present, and 32.9% were non-families. 29.3% of all households were made up of individuals and 14.7% had someone living alone who was 65 years of age or older. The average household size was 2.52 and the average family size was 3.13.
In the city the population was spread out with 27.2% under the age of 18, 10.9% from 18 to 24, 25.8% from 25 to 44, 19.3% from 45 to 64, and 16.8% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 88.0 males. For every 100 females age 18 and over, there were 83.3 males.
The median income for a household in the city was $30,571, and the median income for a family was $37,137. Males had a median income of $30,480 versus $21,459 for females. The per capita income for the city was $15,154. About 17.0% of families and 20.5% of the population were below the poverty line, including 29.5% of those under age 18 and 12.7% of those age 65 or over.
The main campus for North Central Texas College is located on the west side of Gainesville.
The courthouse grounds feature one of the most impressive Confederate soldier memorials in Texas, erected in the early 20th century by the United Daughters of the Confederacy (UDC), topped by a Confederate soldier facing northward, and bearing the following poetic inscription honoring Confederate casualties of war:
"God holds the scales of justice; He will measure praise and blame; And the South will stand the verdict, And will stand it without shame. Oh, home of tears, but let her bear This blazoned to the end of time; No nation rose so white and fair, None fell so free of crime."
Other memorials on the courthouse grounds honor veterans of other U.S. wars.
The presence of these monuments praising the Confederacy is ironic, given that Gainesville was the site of a notorious massacre of Texans by Confederate forces. The Confederacy had promised that Texans would not be drafted to fight the United States outside Texas. When it broke this promise Confederate officials feared that Cooke County, known to be loyal to the United States, would be the site of protests and would possibly secede back to America as several counties in Tennessee already had.
Confederate soldiers rounded up over 200 Texans, and on October 1, 1862 hanged 42 after a mock trial. This event sparked a reign of terror in which dozens of Texans suspected of being loyal to America were lynched by Confederate soldiers.
Gainesville is also home to a large outlet mall (The Gainesville Factory Shops) attracting visitors from north Texas as well as southern Oklahoma. This mall continues to remain open although many shops are closed. Gainesville also boasts state championships in High School Football (3A-I 2003) and High School Basketball (3A 2002).
On one of Germany's biggest commercial television station there is a weekly docu-soap about the Reimann family, which emigrated to Gainesville, Texas, in 2004. They opened a bed and breakfast business at Moss Lake in 2007.
On June 18, 2007, thunderstorms moved through Gainesville, resulting in intense flooding. Over 7 inches fell in Gainesville and nearby Sherman. On June 20 around 5:00 A.M., straight lines winds hit and Wichita Falls had winds up to 94 mph.