Monticello was founded in 1808 as seat of the newly formed Jasper County.

The city was named after Monticello, the estate of Thomas Jefferson.

The climate is characterized by relatively high temperatures and evenly distributed precipitation throughout the year.

[9] The bedrock under Monticello is an intermediate-to-mafic type on which dark red clay with dark reddish brown loam topsoil is mapped as Lloyd series.

[12][13] As of the 2020 United States census, there were 2,541 people, 1,110 households, and 698 families residing in the city.