When the Oklahoma Territory opened for settlement in 1889, the family headed south again. However, Lewis died along the way leaving Adaline to raise the younger children alone. Adaline continued on, placing a claim on the banks of Kingfisher Creek in Indian Territory, where initially she and the family lived in a dugout. By this time the older Dalton brothers were on their own.

For a short time the brothers served on the side of the law, working as U.S. Deputy Marshals. Their older brother, Frank Dalton, was commissioned a Deputy Marshal for the federal court in Fort Smith, Arkansas and Bob Dalton served on several of his posses. On November 27, 1887 in a gun battle with the Smith-Dixon Gang, Frank Dalton was shot and killed in the line of duty.

Grat Dalton followed in Frank's footsteps, first taking his place as a Deputy Marshal in Fort Smith, Arkansas and two years later as a Deputy Marshal for the Muskogee court in Indian Territory in 1889. That same year he received a bullet in his arm while attempting to arrest a suspect. Bob Dalton was also commissioned as a Deputy Marshal for the federal court in Wichita, Kansas, working in the Osage Nation, in 1889.

Bob Dalton, who would later become the leader of the Dalton Gang, was the wildest of the bunch. When he was just 19, he killed a man, claiming it was in the line of duty. Nevertheless, some suspected that the victim had tried to take away Bob's girl.

While Emmett Dalton worked as member of some of his brothers’ posses, he made his living working as a cowboy on the Bar X Bar Ranch near the Pawnee Agency. While working at the ranch, Emmett met two men who would later become members of the gang -- Bill Doolin and William St. Power, alias Bill Power. Power, also known as Tom Evans, had drifted into the area from Texas with a trail herd from the Pecos.

Emmett also made the acquaintance of several other cowboys working on nearby ranches who would later become part of the gang. These included Bill Power, Charlie Pierce, George "Bitter Creek" Newcomb, Bill EcElhanie, Charlie Bryant, and Richard (Dick) Broadwell, alias Texas Jack, alias John Moore.

Charlie Pierce was from the Blue River country in Missouri  but headed to Indian Territory to avoid serving jail time for whiskey peddling.

Dick Broadwell was from a prominent family near Hutchinson, Kansas and at the opening of Oklahoma Territory he staked a claim to a homestead in the Cowboy Flats area. There, he met and a young lady who owned the homestead next to his and asked her to marry him. After their marriage, she persuaded him to sell both claims and move with her to Fort Worth, Texas, where she disappeared with their money. The embittered Broadwell, returned to Indian Territory and started work on the ranches.