In 1930 Czechoslovakia had 13,600 km of railroads (the fifth largest in Europe), of which 81% were state (ČSD)-owned, and the trend was to nationalize the remaining private railroads. Most of the infrastructure was concentrated in the industrial regions of the Czech lands. 87% of the railroads were single-track. 135,000 people were employed on the railroads (around 1% of the population).
When Czechoslovakia broke up in 1939, the Protectorate of Bohemia and Moravia formed the "Bohemian-Moravian Railway" company (in Czech Českomoravské dráhy-ČMD, in German Böhmisch-Mährische Bahn-BMB) under the control of the Deutsche Reichsbahn (DR). In the Slovak State, the company "Slovak Railways" (in Slovak Slovenské železnice-SŽ) was formed. In 1945 the ČSD was re-established.