The main line between Pittsburgh and the Ore Country was completed in the 1880s. The W&E also built secondary mainlines to Detroit, St Louis, Indianapolis, and St Paul. It's main revenues for the first part of the 20th century were ore, forest products, grain, and passengers. Notable passenger trains included the "Badger" between Chicago & Duluth, and the "Great Lakes Limited" between Pittsburgh and St Paul.
In the mid 1950s, the W&E began to cast it's eyes eastward. In 1957, the W&E entered into merger negotiations with two friendly connections in the east, the Shenandoah & Ohio (S&O) and Atlantic & Ohio (A&O). The merger occured in 1961, with the resulting system being the Wisconsin & Ohio Railway.
The 1970s brought little change to the W&O. With the advent of Amtrak, the W&O discontinued it's passenger service. In 1975, the W&O purchased the Milwaukee & Western Illinois Railway, which gave the W&O access to the largest city in Wisconsin.
In the early 1980s, the W&O began to see the storm clouds brewing on the horizon. The W&O decided that it had to once again expand the system, or else possibly end up as the odd-man out.
In 1983, the W&O entered into an agreement to purchase the Chicago & Central Iowa RR (CCI). The merger was a natural fit as it was an end-to-end merger, and gave the W&O access to Kansas City, and the grain fields of Iowa. Upon the merger, the W&O reorganized itself into the Wisconsin & Ohio Rail System. At Kansas City, the W&O picked up a friendly connection with the Southern Pacific Lines.
The W&O tried to stay out of future mergers, but it was inevitable that someone would eventually come calling. After it's defeat to Norfolk Southern in attempting to merge Conrail, CSX decided to opt for plan B, which was to purchase the W&O. CSX's reason for this merger is that it would acheive access to areas west of Chicago that it did not currently serve. The merger announcement came in 1999, and by mid-2000, the W&O was a part of the CSX system.