After the Kelley brothers purchased the land, there was commercial development through extraction of the island's limestone and lumber resources, and the population began to grow with workers and families.

Several ferries provide regular transport to the mainland for most travelers; the island also features a number of marinas, as well as a small airfield for private planes.

The Kelleys Island Historical Association relies on the Henry Rowe Schoolcraft investigations, which dated the carvings to roughly 1643.

He theorized that the rock was used by members of "seasonal" Native American tribes, to impart information to one another about how the hunting had been in the area, and where their group would next be traveling.

The indigenous peoples who are thought to have inscribed these images are said to have been annihilated about 1665 by Iroquois nations from the New York area, who were trying to conquer territory to control the fur trade.

[13] For a while, Cunningham enjoyed friendly relationship with the native people: he built a log cabin near their village, socialized with their hunters, and traded goods with them on a regular basis.

[13] But (as the legend goes) Cunningham had a disagreement with the Native Americans, and a group tore down his home, stole all his possessions, and attempted to kill him.

Prior to the War of 1812, several other white adventurers are documented as trying to settle this island, but all of them were eventually being driven away, either by the native people,[13] or by the incoming U.S. pioneers and land-owners.

During the War of 1812, the west shore of Cunningham Island was developed as a military rendezvous post by US General William Henry Harrison.

[13] In 1818, a man named Killam briefly attempted to start a logging company, but abandoned the island after the large steam-powered boat he used to transport wood to the mainland wrecked and sank.

[13] About the year 1833, Ben Napier, a Scottish-American veteran of the War of 1812,[15] claimed ownership of this "Cunningham Island" (and also nearby Put-in-Bay), through squatters rights.

[21] Shortly afterward, brothers Datus and Irad Kelley became aware of the island's potential worth, and slowly began purchasing its land in parcels.

[22] Irad Kelley first became aware of the island after being forced to seek shelter there while transporting goods via sloop sailboat from Detroit to his shop in Cleveland.

[13] The brothers quickly began improving and expanding the island's docks to export limestone, fruit, and red cedar lumber.

The village's various industries hired a number of immigrants (including young children), many of whom would work on the island during the summer and return to their homeland during the winter.

[13] Among the nationalities working on the island at that time were Irish, Poles, Slavs, Macedonians, Hungarians, Bulgarians, Italians, and Portuguese.

Each summer since 1974 (typically in August), the island hosts a weekend-long homecoming festival, which includes a theme parade featuring both locals and vacationers, a picnic, and a number of food and craft booths.

Fish & Wildlife Service, the Ontario Ministry of Natural Resources, and several other non-profit agencies listed Kelleys as the 7th most ecologically threatened island in the Great Lakes.

[31][32][33] The reasons given for the island's poor ecological health included "development, tourism and recreation, marinas and resorts, increased roads and buildings, incompatible agricultural practices and invasive species.

[36] The boat originally provided transport from Lakeside, Ohio to what is now East Harbor State Park on Catawba Island (which is actually a peninsula).

[36] The company folded in the first decade of the 21st century due to financial mismanagement, excessive growth with low market share, and steep price competition by the recently established Kelleys Island Ferry.

[38][39][40] He was arrested in 1992 for being a felon in possession of over 60 firearms (it is illegal for an individual in Ohio to own any guns if previously convicted of a felony).

[42] A competing ferry line named the Jet Express runs during the season multiple times daily from Sandusky, and Cedar Point to Kelleys Island.

The Jet Express runs from Sandusky, Ohio and makes stops at Cedar Point, Kelleys Island, and Put-In-Bay.

Due to the island's small size, many people use bicycles, golf carts and motor scooters as their regular transportation while there.

These mudflats were permanently submerged and progressively buried beneath muddy shoal and lagoonal sediments as relative sea level rose and the shoreline shifted westward during the Eifelian Stage.

The Bellepoint Member consists of wackestones and packstones, which accumulated as muddy shoals and contain a large number of rugose corals, gastropods, rostroconchs, and brachiopods.

The Marblehead Member consists of a lower, thick-bedded, cherty, dolomitic, heavily-burrowed mudstone deposited in lagoonal conditions below mean wave base.

These mudstones grade upward into thinner bedded, sparsely fossiliferous packstones and grainstones of this member's upper part that accumulated as subtidal shoals.

[48] The Devonian limestone and dolomite that comprise Kelleys Island has been deeply eroded and scoured by the Laurentide Ice Sheet over the Pleistocene.