Prussia nationalized its railways in 1880 in an effort both to lower rates on freight service and to equalize those rates among shippers. However, instead of lowering rates as far as possible, the government ran the railways as a profit-making undertaking, and the railway profits became a major source of state revenue. The nationalization of the railways slowed the economic development of Prussia because the state favoured the relatively backward agricultural areas in its railway building. Moreover, the railway surpluses substituted for the development of an adequate tax system.