In 1855, David Sears purchased title to Benham's Island, situated near the upper or eastern portion of the larger island of Rock Island (now Arsenal Island). Earlier, in 1846, he had built a stone wall dam which connected Benham's Island with Rock Island. The dam provided water power to his flour mill and several other neighboring businesses on the main island. A road built between the two dams formed part of a wagon route stretching from Moline to the steamboat landing at Benham's Island. From here, wagons were ferried across the river to Iowa.

The Sears' mill and dams built at Rock Island attracted other businesses. The water power brought commerce to the island. In 1847, Sears persuaded John Deere and his partners, Robert N. Tate and John Gould, to settle in Moline along the shore of Sylvan Slough.

Despite their holding of property, Sears and other citizens did not hold legal authority to the land on Rock Island. Because of this, they maintained communication with federal officials in an effort to obtain legal titles to the properties. George Davenport and David Sears were the only two citizens who were able to do so. When Sears sold the property on Rock Island back to the federal government, it was at a cost of $145,175 due to improvements on the property. His original purchase price was somewhere around $44.50.