Wartburg is centered near the junction of U.S. Route 27, which connects the city to Kentucky to the north and Harriman and Interstate 40 to the south, and Tennessee State Route 62, which connects Wartburg to Oak Ridge to the east and Middle Tennessee to the west.
According to the United States Census Bureau, the city has a total area of 1.0 square miles (2.5 km²), all of it land.
There were 363 households out of which 29.2% had children under the age of 18 living with them, 35.5% were married couples living together, 16.0% had a female householder with no husband present, and 45.7% were non-families. 43.3% of all households were made up of individuals and 21.2% had someone living alone who was 65 years of age or older. The average household size was 2.12 and the average family size was 2.95.
In the city the population was spread out with 23.0% under the age of 18, 7.3% from 18 to 24, 21.6% from 25 to 44, 20.4% from 45 to 64, and 27.6% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 72.8 males. For every 100 females age 18 and over, there were 62.3 males.
The median income for a household in the city was $19,722, and the median income for a family was $37,917. Males had a median income of $32,708 versus $22,143 for females. The per capita income for the city was $12,252. About 24.5% of families and 29.8% of the population were below the poverty line, including 39.1% of those under age 18 and 19.1% of those age 65 or over.
In 1805, the Cherokee ceded what is now Morgan County to the United States by signing the Third Treaty of Tellico. The first settlers arrived in the area shortly thereafter.
Wartburg was founded in the 1840s by George Gerding, a land speculator who bought up large tracts of land in what is now Morgan County with plans to establish a series of German colonies in the Cumberland region. German and Swiss immigrants arrived at the site by traveling from New Orleans up the Mississippi, Tennessee, and Emory rivers. They named the settlement after Wartburg Castle in Germany. Wartburg was officially incorporated in 1851.
In 1870, Morgan County elected to move its county seat from the (now-defunct) town of Montgomery to Wartburg. The arrival of the railroad in 1880 expanded logging and coal mining operations in the Cumberland region, moving Morgan County away from an economy based on subsistence agriculture to a wage-based economy.
Today, Wartburg is the headquarters for the Obed Wild and Scenic River (managed by the National Park Service), Frozen Head State Park, and Lone Mountain State Forest. The Catoosa Wildlife Management Area is located immediately to the west, and the Big South Fork National River and Recreation Area is located several miles to the north.