In 1888, surveyors for a new railroad came to the rural area of Williamson to survey the land. Wallace J. Williamson saw the men and learned of what was about to happen. The "iron horse" as the locals called it was coming. Williamson then started a land company, calling it the Williamson Manufacturing Company. He divided the land up into lots and sold them at public auction. Most went for $250. Some in the railroad's path went for as little as $25, but they proved the most profitable. By the end of 1888, construction had begun on the railroad and houses and buildings were being erected.
Williamson was incorporated as a town in 1892. The railroad was also completed that year. The first passenger train stopped in Williamson on September 25, 1892. A frame train station was built on Third Avenue, where the present-day offices of the Williamson Daily News are. The town continued to grow. By 1894, there were four regular trains that stopped in Williamson.
On June 20, 1894, a bill was passed by the state legislature to sever a 423.5 square mile area from Logan County that surrounded Williamson. The new county was to be named "Mingo". The bill was held up until March of 1895 due to some discussion in the legislature. After the new county was made official, Governor William Alexander McCorkle appointed the Mingo County officials. J.K. Anderson, J.L. Deskins, and Alex Stafford were appointed as County Commissioners. Leo Drake was appointed as the County Clerk.N.J. Keadle was elected sheriff and W. Brazie was appointed as county surveyor. James Varney was named Assessor. Dr. George W. Lawson was physician and surgeon to the county's poor and jail inmates. J.M. Hatfield was given the position as Circuit Clerk and Thomas H. Harvey was named judge. John Stafford was named the Prosecuting Attorney.
The area that is Mingo County was part of Montgomery County, Virginia in 1776. In 1824, it was changed to Logan County, which it remained a part of for seventy-one years.
The jail was built in 1895 on the property that is behind the current court house. The first court house was a frame building that was near the site of the present-day Mountaineer Hotel.
Sometime in the late 1890's, the town's first water lines were laid. The first water plant was built in 1900. A man by the name of Thomas B. Garner played an important role in the history of Williamson. Garner and his wife published the town's first weekly newspaper, the Williamson Enterprise. He was also responsible for bringing electricity to the town. Around 1900, Garner started the first power company. Williamson and Matewan were linked by telephone in 1900. Garner also started an ice plant which opened in 1904.
The first private telephones were installed in 1903. Prior to that, only businesses had telephones. A year earlier, in 1902, two landmarks were erected in Williamson. A new court house, complete with a clock tower was built on Second Avenue. On Fifth Avenue, the Olympic Opera House was built. The Olympic building remains on Fifth Avenue to this day.
The first road to be paved was Third Avenue from Pike Street to Logan Street. This occurred in 1903. Also, the First National Bank opened in 1903, as did the Presbyterian Academy, a private school. In 1904, a new building was erected on Oak Street for the Academy.
Another newspaper, the Mingo Republican, was started in 1904. Around the same time, Second Avenue, Third Avenue, Fourth Avenue, Pike Street, Logan Street, and Harvey Street were paved.