The 1840s British speculative boom and collapse centered on railway companies was called Railway Mania.
Railway Mania peaked in the middle of the 1840s as investors poured money into proposed railway lines. Parliament approved hundreds of projects, and promoters advertised railways as opportunities for rapid economic growth and reliable investment income. Many schemes were legitimate, but others depended on unrealistic traffic forecasts or incomplete financing.
When economic conditions weakened and interest rates rose, confidence declined. Share prices fell, and numerous projects were abandoned, delayed, merged, or completed on a smaller scale. The episode affected investors, construction firms, landowners, and the developing British railway network.
Railway Mania is sometimes described as a stock-market crash by itself, but it was more precisely a speculative boom followed by a broad collapse in railway shares and investment. It also left a lasting physical legacy: many railway routes built during the period became important parts of Britain’s transport system.