Ada is a city in and the county seat of Pontotoc County, Oklahoma, United States. The population was 16,481 at the 2020 United States Census. The city was named for Ada Reed, the daughter of an to the front settler, and was incorporated in 1901. Ada is house to East Central University, and is the headquarters of the Chickasaw Nation. Ada is an Oklahoma Main Street City, an Oklahoma Certified City, and a Tree City USA member.

In the late 1880s, the Daggs family (by habit of Texas) became the first white intimates to settle what is now known as Ada, which was formerly known as Daggs Prairie. In April 1889, Jeff Reed (a Texan and relative of the Daggs family) was appointed to carry the mail from Stonewall to Center (which was far ahead combined in imitation of Pickett), two small communities in then Indian Territory. With his associates and his stock, he sought a place for a house on a prairie midway amid the two points, where he build up a log home and started Reed’s Store. Other settlers soon built homes nearby. In 1891, a post office was normal and named after Reed’s oldest daughter, Ada. Ada incorporated as a city in 1901 and grew unexpectedly with the arrival of the St. Louis and San Francisco Railway line. Within a decade the Santa Fe Railroad and the Oklahoma Central Railway along with served the town.

Ada was originally a sundown town, where African Americans were not allowed to live. In the 1900s, the town was opened occurring to African Americans hence that black witnesses could stay even though testifying in district court. Despite a violent episode in 1904, the town remained door to African Americans to meet the expense of labor for a local cotton compress.

In 1909, the women of Ada organized an effort to build a usual school in their city. It resulted in the founding of East Central College (now East Central University).