Adel is the county seat of Cook County and was incorporated on October 3, 1889. The original name of the city was Puddleville. The city’s first postmaster, Joel “Uncle Jack” Parrish, wanted to change the name of the city. It is believed that he saw the name “Philadelphia” on a crocus sack, struck out the first and last four letters to create the present name of Adel.

The Jim Paulk-Sowega Building, built in the 1930s, now houses the Adel-Cook County Chamber of Commerce. The building, popularly known as the Watermelon Building, has an exterior of green watermelon motifs.