[3] According to the United States Census Bureau, the city has a total area of 1.14 square miles (2.95 km2), all land.

There is a network of paved farm to market roads starting in Allerton and connecting with the surrounding towns.

Allerton was a division point on the Chicago, Rock Island and Pacific Railroad until the bankruptcy of the line in 1980.

The old Golden State Route that ran east from Allerton through Seymour, Fairfield and Chicago was then abandoned.

It was purchased by the Chicago & Northwestern after the bankruptcy as a direct line between Kansas City and Minneapolis.

It has seen a marked increase in traffic since the Chicago & Northwestern merger with Union Pacific.

The last passenger train on the old Rock Island system through Allerton was the Plainsman from Kansas City to Des Moines and Minneapolis.

The southeastern side of the town was heavily damaged by an EF2 tornado on March 5, 2022.

28.1% of all households were made up of individuals, and 13.4% had someone living alone who was 65 years of age or older.

30.7% of all households were made up of individuals, and 17.3% had someone living alone who was 65 years of age or older.

Kindergarten and the lower elementary grades for the Allerton children continued to be held in the Allerton school along with seventh and eight grade for the entire Wayne Community School District beginning in 1967.

This arrangement continued until the Allerton School building was deemed deficient and all classes are now held in Corydon.