[2] The county is named for an influential Muscogee Creek family, whose members led the migration of the Lower Towns to Indian Territory and served as leaders for generations.

[4] Many archaeological sites in McIntosh County date back to the Archaic period in North America (6000 BC - 1 AD).

Indigenous people may have made petroglyphs at the Handprint Site before the coming of the earliest European explorers.

[3] In 1825, the Creek of the Lower Towns in the territory of present-day Georgia, led by William McIntosh, agreed by the Treaty of Indian Springs with the United States, to exchange their land in Georgia for land in Indian Territory.

There the Creek repeatedly battled with the Osage, who had historically occupied a large area including this and up through present-day Missouri.

In 1836, the Creek established North Fork Town on the Texas Road, about two miles east of present-day Eufaula, Oklahoma.

[3] Albert Pike, representing the Confederate States of America, signed treaties with the Chickasaw, Choctaw and Creek nations at the beginning of the Civil War.

The Union Army won and took control of that part of Indian Territory north of the Arkansas River.

[3] Between 1907 and 1909, the people of Checotah were involved in a dispute with nearby Eufaula known as the McIntosh County Seat War.

Soon after, a group of heavily armed men from Chectotah attempted to seize the records from the courthouse in Eufaula, but were beaten back and forced to surrender during the gunfight that followed.

[7] The county is mostly within the jurisdiction of the federally recognized Muscogee (Creek) Nation, which oversees and represents its members.

However, construction of a dam and the resulting Eufaula Lake inundated much of the best cropland, causing a large-scale decline in agriculture.

[3] Completion of Eufaula Lake in 1964 generated revenue from hydroelectric power, stimulated tourism, and produced companion businesses like boat building and general retail.

While there are ample coal deposits, much of it has a high ash and sulfur content, so little except the low-sulfur type has been mined.

[3] The following sites in McIntosh County are listed on the National Register of Historic Places: