The latest report by the state, based on comparing voter registration rolls with DMV databases, puts the number of registered voters without state photo ID at more than 758,000 — 9.2% of the registered voters in the state.  186,830 of those voters are apparently in Philly — 18% of the city’s registration.

Looks like the comparison was done by trying to match name and date of birth from one list to another.  Depending on how the match was conducted, that will count some people as matches who shouldn’t be (two different people with the same name and date of birth), and some people as non-matches who should be (the same person, but with a typo or middle name or nickname on one list); the extent to which the two different types of errors will cancel each other out, leaving a roughly accurate total estimate, is not clear.