You know the old chestnut about fewer than 10% of Americans owning a passport ? C.P.G Grey took a data set about issued passports from data.gov and did some calculation to get at the real numbers. He then plotted the results on an map showing percentages of passport owners by state.
A hefty caveat: his spreadsheet shows a figure of 213% ownership for Washington DC suggesting his method might be flawed. Even taking account of all the diplomatic passports it seems a little high. But as with his earlier work he’s not claiming to be an expert, and is welcoming suggestions.