Niles City, three miles north of the business center of Fort Worth in central Tarrant County, was incorporated in February 1911. The town was called "the richest little city in the state of Texas" because of the high value of several corporations within its boundaries. It was named in honor of Louville Veranus Niles of Boston, Massachusetts, a large stockholder in the Fort Worth Stock Yards Company; Niles was given credit for the fact that the Swift and Armour packing companies located their plants in the vicinity. The Fort Worth Stockyards, including the Live Stock Exchange Building and the packing plants, all located within the Niles City corporate limits, were valued at over $12 million in 1911.
Niles City originally comprised a little over one-half square mile and had a population of 508 inhabitants. It was governed by a mayor, a city marshall, and five aldermen. Its first election was held on April 4, 1911. Six railway companies operated lines through Niles City: the Belt Railway; the Northern Texas Traction; the St. Louis and Southwestern of Texas Railway; the Gulf, Colorado and Santa Fe Railway; the Fort Worth and Denver City Railway; and the Chicago, Rock Island and Gulf Railway. The Belt Railway also owned and operated a roundhouse in Niles City. The Northside Coliseum, now known as Cowtown Coliseum, was located in Niles City and was the site of the Fat Stock Show, the first indoor rodeo and the first indoor horse show in the state. Many famous personalities performed in the coliseum while it was located in Niles City, including Enrico Caruso, who sang before a crowd of about 8,000 in 1920. The town attracted a number of home builders because of the many utilities and conveniences that it offered, but only a few private homes were located within the town, since most of the property was owned by private corporations, from which most residents rented living quarters. The packing plants contributed greatly to the town's economy and employed workers from Fort Worth and the surrounding suburbs; 4,000 men and women were reported working for Swift and Armour at one time. Other industries located in Niles City included two grain elevators, the Fort Worth Cotton Seed Oil Company plants, and the Gulf Oil Company, which constructed a second refinery and a pipeline plant a short distance from the limits of Niles City in 1911. Gulf also had a track in the railroad yards. The extraterritorial industries were taken in when the town extended its boundaries in 1921, as were the schools which the children of Niles City attended, in the Diamond Hill and Washington Heights school districts.
In January 1921 the Texas legislature passed a bill which allowed any city with a population of more than 50,000 to take in adjacent territory that did not contain a town of more than 2,000 inhabitants. This bill enabled Fort Worth to annex Niles City. To block annexation, Niles extended its city limits and gained the needed population. In July 1921, however, a second bill was passed that raised the population needed to block annexation to 5,000. In the early part of 1922 Fort Worth city officials and members of the Greater Fort Worth Commission began holding meetings with suburbs considered for annexation, hoping to build support. In June 1922 an ordinance was adopted and passed by the commissioners of Fort Worth ordering a special election to decide on a number of proposed amendments to the city charter, including the annexation of Niles City and a large part of the two school districts. The election was held in July, and all proposed changes were passed. In spite of litigation to block annexation, Niles City became a part of Fort Worth on August 1, 1923.