This city was voting to fill six seats, including that of the president and the mayor. Voters presented identification cards and were handed six large ballots, one for each open office. The names of candidates were also color-coded to assist the illiterate. Voting booths were small, waist-high writing tables enclosed by hanging plastic sheets printed with the reassuring words, "The vote is free and secret." Voters emerged from the booths, folded the ballots and slid each one into the box corresponding to the contested seat. To complete the process, thumbs were marked with indelible ink and ID cards were returned. Observers from each party monitored the flow.
I wonder why it's ok to show an ID to vote in Mexico but not here?