Greeley began as the Union Colony of Colorado, which was founded in 1869 by Nathan C. Meeker, an agricultural reporter for the New York Tribune, as an experimental utopian farming community "based on temperance, religion, agriculture, education and family values," with the backing of the Tribune's editor Horace Greeley, who had visited Colorado in the 1859 Pike's Peak Gold Rush and had popularized the phrase "Go West, young man".

[8][9][10] A committee which included Meeker and former Civil War general Robert Alexander Cameron traveled to Colorado to find a suitable site, and purchased 12,000 acres at the confluence of the Cache la Poudre and South Platte Rivers.

[15] On December 12, 2006, the Immigration and Customs Enforcement (I.C.E) staged a coordinated predawn raid at the Swift & Co. meat packing plant in Greeley and at five other Swift plants in western states, interviewing undocumented workers and transporting hundreds off in buses.

[17] In June 2012, Greeley became the first city in the state of Colorado to implement SB11-273, known as the Law of Common Consumption,[18] allowing for patrons of the Downtown Greeley Entertainment District to buy drinks in "Go-Cups" from participating downtown establishments.

On 28 May 2024, a severe hailstorm impacted the eastern side of the city, covering some areas in over one foot of hail (~30.5 cm) and causing one fatality.

[19] Mayor John Gates signed a local disaster declaration due to major flooding and hail.

[20] Greeley is located in the High Plains of northern Colorado about 25 mi (40 km) east of the Rocky Mountains and north of Denver.

Extratropical cyclones which disrupt the weather for the eastern two-thirds of the US often originate in or near Colorado, which means Greeley does not experience many fully developed storm systems.

The Chinook winds coming off the mountains often raise temperatures to near 70 °F (21 °C) in January and February, and sometimes to near 90 °F (32 °C) in April.

The diurnal temperature range is usually rather wide, with a 50-degree (Fahrenheit) difference between daytime highs and nighttime lows not uncommon, especially in the spring and fall.

The racial makeup of the city was 64.1% White, 2.8% Black or African American, 1.2% American Indian and Alaska Native, 1.4% Asian, 0.1% Native Hawaiian and Pacific Islander, 13% from other races, and 17.3% who identified as two or more races.

[29] Of Greeley residents age 25 and over, 23% were high school graduates (no college) and 26% had a bachelor's degree or higher.

[30] Among the companies based in Greeley are the meatpacker JBS USA (originally Monfort of Colorado, Inc.), the contractor Hensel Phelps Construction, and the Colorado/Kansas operations of natural gas utility Atmos Energy.

[32] According to the city's annual list of top employers,[33] the following are the largest employers in Greeley as of May 1, 2023: The 233rd Space Group is a unit of the Colorado Air National Guard located at Greeley Air National Guard Station.

This locally famous event typically lasts nearly two weeks leading up to Independence Day.

Including events like a demolition derby, rodeos, carnival rides and games, food vendors, live musical performances, and even a 4th of July parade, this yearly tradition has grown to draw-in visitors from neighboring cities and states.

[35] Greeley is home to the Union Colony Civic Center, one of the largest performing arts venues in Colorado.

The 214-seat Hensel Phelps Theatre hosts the Stampede Troupe in addition to lectures, meetings, and smaller performances.

The Tointon Gallery presents a dozen exhibits annually by local, regional, and national artists, and is free to the public.

[47] Since January 2, 2020, GET operates a regional bus service called the Poudre Express which connects Greeley to Fort Collins and Windsor.

Express Arrow also operates buses to Denver and Buffalo, Wyoming, stopping at multiple other cities along the way.

A fictionalized Greeley was featured heavily in the season 15 finale episode of the popular animated television show South Park, titled "The Poor Kid".

The episode sees main characters Kenny McCormick and Eric Cartman move to the town, after being put into foster care.