The 'Leary' excavation is the main 'Oneota'-(oh-oh-nee-tah) reference to the Missouri River. The Oneota were a 'Mississippi' equal culture that flourished from 1000 to 1650 AD. Oneota are the ancestors of Siouane-speaking tribes. The site is located near present Rulo. Around 1640, the area around the later Rulo is the property of the Omaha tribe.
E. H. Johnson, residing at Rulo, was the first practical surveyor and engineer who came to the County. In the fall of 1856, Mr. Johnson surveyed the townsite of Rulo (named from Charles Rouleau, one of its proprietors) for Charles Martin, Charles Rouleau, Wm. Kencelear and Eli Bedard, proprietors of the town. The current village of Rulo was mapped in 1856 during the implementation of the "Prairie du Chien treaty" (1830) and was created in 1857 on prairie owned by Amelia (Emilie) Menard, wife of Charles Rouleau (old Charley Rulo ). Amelia was a Yankton Sioux and probably born on March 7, 1834. Charles Rouleau was born in Detroit in 1824 and he died on June 29, 1873 in Rulo. He was buried in the cemetery of Rulo, but there is no tombstone. On January 8, 1858 Rulo got the status of village, on November 1, 1858 it became a city. The first name of the village was Rouleau, but by pronouncing the name by the many nationalities in the village, the phonetic pronunciation "Rulo" is now commonplace. In 1859 the territory was finally extended with the country owned by mrs. Sophie Menard, sister of mrs. Rouleau. Sophie Menard was married to Eli Bedard, born in Quebec in 1825: he also played an important role in the founding of the village. Rulo was a stop during the period of expansion to the west. In 1885 building started on a bridge across the Missouri River, CBQ (Chicago, Burlington and Quincy Railroad) was the building company. During the years it took to complete the project, the population in Rulo was as high as 1,800. When the bridge opened October 2, 1887, it put Rulo on a "main line railroad," which continued to improve the economy of the town.
The first store was owned by Martin Berry & Gold. Later on came Easley & Sherer. The first village blacksmith was Joseph Brazo.