Many of the farthest-reaching changes that took place during the Second Empire derived, directly or indirectly, from France's new railway network, and indeed the universal exhibitions could not have taken place on such a scale if it had not been for steam transport. The first French passenger line had opened under the July Monarchy, but the real expansion occurred between 1852 and 1870 in a great surge of growth that added 15,000 kilometres to the system. A line from Paris to the German border was completed in 1853 and another linked the capital with the Mediterranean during the Crimean War; by 1860 the network had reached Italy and Spain; and by the end of the Second Empire the modern pattern of the French railway was already in place. Its impact was immense. Production of iron and steel soared, and speculators made and lost fortunes as the railways transformed trade and commerce. City centres were rebuilt to accommodate stations and equipment yards, and the French landscape changed dramatically as new lines and tunnels and cuttings sliced through it.

But the railway's effects were not merely physical or financial, for the expansion of the rail network brought with it a broadening of social and mental horizons. Goods and passengers could now move from one end of the country to the other with unprecedented ease as the railways brought people and produce from different parts of the country – or indeed from different countries – together as never before.