We find that registered voters booked into county jails during 2020 voting days for the full duration of voting days were on average 46% less likely to vote in 2020, relative to registered voters booked into the same jails just after Election Day. Black registered voters booked into county jails during 2020 voting days for the full duration of voting days were on average 78% less likely to vote in 2020, relative to Black registered voters booked into the same jails just after Election Day. Even when individuals in jail are aware that they can vote, access to registration materials and to voting mechanisms such as voting machines, mail-in or absentee ballots are also restricted in jails.