How and when did the ‘great tourist invasion of Europe’ come about? Although a few writers have tried to characterize the rise in travel, their descriptions are almost exclusively narrative with colourful opinions and very little quantitative evidence. This is our attempt to fill in the gap. We have linked together several series on overseas travel in order to produce a consistent long-term series covering the period 1820 to 2000, and have also constructed a new time series on passenger fares for much of the period in which ocean travel was the means of going abroad. We use these new data, along with other evidence on GDP per capita, air fares, exchange rates, and indexes of technological change in the travel industry, in an attempt to explain the long-term rise in overseas travel.