With the army providing frontier security, Belknap rapidly grew by 1859 to comprise five general stores, two blacksmith shops, a hotel, Charley Neuhaus' billiard parlor, a Methodist church, a jail, a courthouse, a school that met at the fort, and 150 people. The community became a stop on the famous Butterfield Overland Stage route to California.

On September 14, 1859, Major Robert Simpson Neighbors was alledgedly killed by Edward Cornett during to Neighbor's policies toward the Indians. There were no eyewitnesses to the murder according to County Clerk Burkett.  Major Neighbors is buried in the Belknap cemetery.

Fort Belknap's first decommission was in 1856.          The removal of the federal fort hampered the growth and security of the community of Belknap. The post office was discontinued at Belknap in 1865 when Young County became disorganized.

Confederate soldiers with the Frontier Regiment occasionally camped in the area, the few families staying in the area mainly lived on the fort grounds for protection against Indians. Little community activity was evident when federal troops returned to Fort Belknap in 1867 for six months, until the fort was decommissioned for the last time.

By 1872 the settlement had recovered and the post office was re-established in 1874. That same year , the residents of the area voted to re-organize Young County and an election for held for the county seat. Belknap lost the election to Graham, Texas. In 1892, the town had a hotel, several stores and 125 people. But Belknap consolidated with the new settlement of Newcastle in 1908, when the discovery of coal prompted the Wichita Falls and Southern Railway to build into Young County.

The Belknap post office was discontinued and moved to Newcastle on March 3, 1908. In 1915, the land upon which Belknap was located was purchased and the County Commissioners Court de-platted the town.

The cemetery, near the original site, is all that remains of the  frontier town of Belknap.