A survey by the Brennan Center has revealed that more than 9% of American citizens of voting age don't have proof of citizenship readily available, including passports, birth certificates, or naturalization papers. That means that, among other things, 21.3 million Americans would be denied voting registration if required to show a document as proof of citizenship.
What's more, the study highlighted racial disparities in the availability of citizenship documents. While just over 8% of white American citizens lack readily available documentation, this figure rises to nearly 11% among Americans of color.
