The US tolerates more inequality than Europe and believes its economic mobility is greater than Europe's, though they had roughly equal rates of intergenerational occupational mobility in the late twentieth century. We extend this comparison into the nineteenth century using 10,000 nationally-representative British and US fathers and sons. The US was more mobile than Britain through 1900, so in the experience of those who created the US welfare state in the 1930s, the US had indeed been "exceptional." The US mobility lead over Britain was erased by the 1950s, as US mobility fell from its nineteenth century levels.