During the American Civil War, the future location of Cullman was the site of the Battle of Day's Gap. On 30 April 1863, Union forces under the command of Colonel Abel Streight won a victory over forces under Confederate General Nathan Bedford Forrest. This battle was part of a campaign and chase known collectively as Streight's Raid. Although Streight got the upper hand in this battle, Forrest would have the last laugh. In one of the more humorous moments of the war, Streight sought a truce and negotiations with Forrest in present-day Cherokee County near present-day Gaylesville. Although Streight's force was larger than Forrest's, while the two were negotiating, Forrest had his troops march repeatedly in a circuitous route past the site of the talks. Thinking himself badly outnumbered, Streight surrendered to Forrest on the spot.
Cullman itself was founded in 1873 by Colonel John G. Cullmann, a German refugee who arrived in America. (The city's name was Americanized to "Cullman", although some sources state that Cullmann had earlier Americanized his name from "Kullmann". Stanley Johnson, his only surviving American descendant, told The Cullman Times in 1998 that there are no German records indicating "Kullmann", and that "Cullmann" was always the correct spelling.) Cullmann had been an advocate of democratic reforms in his native Germany, who fled when the autocratic Prussian-dominated regime emerged ascendant after the Revolutions of 1848. In 1873, Cullmann purchased of land from the Louisville and Nashville Railroad Company, on which he established a colony for German immigrants.
Five German families moved to the area in March 1873; in 1878, the town was incorporated and named after Colonel Cullmann. Over the next twenty years, Cullmann encouraged around 10,000 Germans to immigrate to the United States, with many settiling in the Cullman area. Cullmann drew on his military engineering training in laying out and planning the town. During this period, Cullman underwent considerable growth. German continued to be widely spoken, and Cullmann himself was the publisher of a German-language newspaper. When Cullmann died in 1895, at the age of 72, his funeral was marked by the attendance of Governor William C. Oates. The site Cullmann selected for his headquarters is now his gravesite.
For many years Cullman was a college town, with Saint Bernard College serving as the home of several hundred students. In the mid-1970s, it briefly merged with Sacred Heart College (a two-year Benedictine women’s college), to become Southern Benedictine College. That college closed in 1979, and it now operates as the Saint Bernard Preparatory School. The former site of Sacred Heart College is now the Sacred Heart Monastery, which serves as a retreat center operated by the Benedictine Sisters of Sacred Heart Monastery.
During the twentieth century, Cullman developed a more diverse economy, including several manufacturing and distribution facilities. However, its economy remains primarily based on agriculture and providing services to the agricultural workforce. Cullman County has the highest agricultural production in the state, and is one of the sixty largest agricultural-production counties in dollar terms in the United States.
Cullman gained national attention in early 2008, when a special election was held to fill a vacancy in the Alabama House of Representatives. Cullman County has only a 1% African-American population, a fact which outsiders have used to portray the area as an intolerant backwater, even alluding to disputed reports of Ku Klux Klan influence (despite its significant Catholic population). Those allegations were laid to rest when the district that included Cullman elected James C. Fields, an African-American, in that special election by an overwhelming margin.
Cullman's German heritage was repressed during both World War I and World War II, as the United States was fighting Germany. This was reversed in the 1970s, with renewed interest in the city's history and heritage. Today, Cullman holds an annual Oktoberfest—although without the traditional beer, since as Cullman is in a dry county. An honorary "Bürgermeister" is elected for each Oktobetfest.
Cullman is located on top of Brindley Mountain plateau at (34.177508, -86.844996). This is a close offshoot of the long geographic ridge called Sand Mountain, a southmost extension of the Appalachian Mountains. The elevation is , close to the watershed between the Tennessee River and the Black Warrior River. Cullman provides its own town water supply from a city-owned lake within the city limits, Lake Catoma.
According to the U.S. Census Bureau, the city has a total area of . of this is land, with water making up 4.5%, or .
The Cullman City School System operates five schools: Cullman Primary School (Pre-K - First Grade), East Elementary (Second Grade - Sixth Grade), West Elementary (Second Grade - Sixth Grade), John G. Cullman Middle School (Seventh and Eighth Grades) and Cullman High School (Ninth Grade - Twelfth Grade). Other schools include Saint Bernard Preparatory School, a Benedictine boarding school (Ninth Grade - Twelfth Grade), Saint Bernard Middle School (Seventh and Eighth Grade), Sacred Heart Elementary School (Pre-K - Sixth Grade), and Saint Paul's Lutheran School (Pre-K - Sixth Grade).
As of the census of 2000, there were 13,995 people, 6,059 households, and 3,762 families residing in the city. The population density was 765.0 people per square mile (295.3/km²). There were 6,679 housing units at an average density of 365.1/sq mi (140.9/km²). The racial makeup of the city was 96.43% White, 0.36% Black or African American, 0.24% Native American, 0.45% Asian, 0.04% Pacific Islander, 1.06% from other races, and 1.41% from two or more races. 4.85% of the population were Hispanic or Latino of any race.
There were 6,059 households, out of which 26.2% had children under the age of 18 living with them, 48.3% were married couples living together, 10.7% had a female householder with no husband present, and 37.9% were non-families. 35.2% of all households were made up of individuals and 18.0% had someone living alone who was 65 years of age or older. The average household size was 2.22 and the average family size was 2.85.
In the city the population was spread out with 21.8% under the age of 18, 8.2% from 18 to 24, 25.3% from 25 to 44, 22.6% from 45 to 64, and 22.1% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 87.5 males. For every 100 females age 18 and over, there were 81.4 males.
The median income for a household in the city was $29,164, and the median income for a family was $41,313. Males had a median income of $32,863 versus $21,647 for females. The per capita income for the city was $18,484. About 9.4% of families and 13.2% of the population were below the poverty line, including 12.3% of those under age 18 and 18.5% of those age 65 or over.