Thornton consisted solely of farmland until 1953 when Sam Hoffman purchased a lot off Washington Street about seven miles (11 km) north of Denver. The town he laid out was the first fully planned community in Adams County, and the first to offer full municipal services from a single tax levy, including recreation services and free trash pickup. Thornton was named in honor of Former Colorado Governor Dan Thornton.
The Thornton Community Association (TCA) was formed in 1954 to help guide the new community's development. By the end of 1955, Thornton had 5,500 residents in over 1,200 homes. The TCA was instrumental in Thornton's 1956 incorporation as a city. Oyer G. Leary was elected the first mayor.
Thornton is located at 39°54′11″N 104°57′16″W (39.903043, -104.954406).
According to the United States Census Bureau, the city has a total area of 27.2 square miles (70 km2), of which, 26.9 square miles (70 km2) of it is land and 0.3 square miles (0.78 km2) of it (1.25%) is water.
As of the 2010 census, there were 118,772 people, 41,359 households, and 30,254 families residing in the city. The population density was 3,409.1 people per square mile (1,316.8/km²). There were 43,230 housing units at an average density of 1,240.8 per square mile (479.3/km²). The racial makeup of the city was 77.4% White, 4.4% Asian, 1.8% African American, 1.1% American Indian, 0.1% Pacific Islander, 11.4% from other races, and 3.8% from two or more races. Hispanics and Latinos of any race were 31.7% of the population.
There were 41,359 households out of which 43.9% had children under the age of 18 living with them, 54.7% were married couples living together, 6.2% had a male householder with no wife present, 12.2% had a female householder with no husband present, and 26.9% were non-families. 20.1% of all households were made up of individuals, and 4.2% had someone living alone who was 65 years of age or older. The average household size was 2.86, and the average family size was 3.32.
The distribution of the population by age was 29.5% under the age of 18, 9.1% from 18 to 24, 32.6% from 25 to 44, 22.3% from 45 to 64, and 6.5% who were 65 years of age or older. The median age was 32.0 years. The gender makeup of the city was 49.5% male and 50.5% female.
The median income for a household in the city was $65,578, and the median income for a family was $74,233. Males had a median income of $49,154 versus $39,596 for females. The city's per capita income was $26,100. About 7.8% of families and 9.9% of the population were below the poverty line, including 14.1% of those under age 18 and 7.4% of those age 65 or over.
Thornton has 81 city parks and nearly 2,000 acres (8.1 km2) of parks and open space. There are over 80 miles (130 km) of trails throughout the city. Thornton has several recreational facilities like the Margaret Carpenter Recreation Center and the Thornton Community Center. Thornton has several golf courses for golfers like Thorncreek Golf Course and Todd Creek Golf.
Major highways in Thornton are I-25, I-76, SH 7, SH 44, SH 224, and E-470.
Thornton is served by the Denver Regional Transportation District (RTD), which provides bus service to Thornton and the rest of the Denver metropolitan area.
The major airport that serves Thornton is Denver International Airport.
Thornton is served primarily by three school districts: Adams County School District 12, Mapleton Public Schools, and Brighton School District 27J. Encompassing four high schools Thornton High School, Vantage Point High School, Skyview High School, and Horizon High School, five middle schools and fourteen elementary schools. Thornton has several charter schools in or near Thornton. The charter schools are: Stargate School, Colorado Virtual Academy, New America School, Westgate Community Charter School. Thornton has several libraries and is served by the Rangeview Library District.
Thornton has several shopping areas, such as Larkridge Mall, Thornton Town Center, and Thorncreek Crossing Shopping Center. Larkridge is home to national anchor tenants, big box retailers, restaurants, and has a pedestrian village. Larkridge is anchored by Colorado's first Sears Grand store, Dick's Sporting Goods, Bed, Bath & Beyond, PetsMart and others.
Notable individuals who were born in and/or have lived in Thornton include:Tesho Akindele (1992- ), soccer forward
Josh Bredl (1991- ), pro wrestler
Edward Casso (1974- ), Colorado state legislator
John Denney (1978- ), football long snapper
Beth Martinez Humenik, Colorado state legislator
Mike Manning (1987- ), actor
Nikki Marshall (1988- ), soccer forward, defender
Mike McCoy (1953-2016), football cornerback
Adrian Mora (1978- ), welterweight boxer
Joseph Salazar, Colorado state legislator
Kyle Sleeth (1981- ), baseball starting pitcher
Neal Ulevich (1946- ), photojournalist