A major strike in 1919 hit the railroad. Operations ceased for five months, putting the railroad on the brink of bankruptcy. To remain in business, the old coal mines originally owned by Colonel Davis were sold, since the current owners were railroad men and not coal miners. Creditors demanded more, and late tht year the Baltimore & Ohio Railroad, who was interested in some of the CB&W routes bought a 15% share of the railroad. The relationship between the two companies was contentious with the CB&W management wanting to expand to St. Louis and the B&O people vetoing the plan. In 1927, the CB&W purchased back from the B&O the 15% share, with the B&O taking the branch from Rapidan to Culpepper. This cleared the way for expansion to St. Louis.
The railroad prospered and added new customers daily. The company purchased land for the right of way to St. Louis; however, before any track could be laid, nation was hit with the Great Depression. Some of the railroad's oldest customers \went out of business and those that remained were either late paying their bills or didn't pay them at all. The CB&W management cut the labor force to the bone; locomotives and rolling stock were put in storage, and several branch lines were closed.
The harsh economic measures saved the company, and when World War II began, the railroad was positioned to support the war effort. All the locomotives and rolling stock available were pressed into service. Because of the Country's need for another route from St. Louis to the Atlantic coast, the federal government gave the CB&W special permission to complete the mainline to St. Louis. During the war the company set new records in passengers and freight tonnage moved. These records however, put a severe strain on the railroad and by 1945 the CB&W badly needed to modernize its roster.
The transition from steam to diesel locomotives began in March 1946 with the purchase of three FA-1 and FB-1 Alco locomotive sets. This modernization continued and on May 16, 1959 an era ended: The road's last steam train ran between Keezletown and Davis on the Davis Branch. To finance the modernization, the railroad went public in 1946, being listed on the New York stock exchange (symbol CBW).
The 1950's saw a decline in passenger traffic. Passenger service had started in 1899 with biweekly passenger trains between Keezletown and Phoebus. It gradually increased and when the line was completed to St. Louis the CB&W began two daily trains, one east bound and one west bound. At the start of WW II, passenger service between Phoebus and St. Louis had increased to four trains each day. There were also numerous locals along the line. The passenger traffic peaked in 1945. By the 1960's passenger service was unprofitable and the CB&W stopped passenger service on September 3, 1970. Amtrak began daily service on CB&W track between Phoebus and St. Louis in 1972 with a train called "The Mountaineer."