I've worked at the polls since 2004, and ran the polling place (as Chief Judge) since 2005. This is in Raleigh (Wake County), North Carolina. Here I'll tell you all about some of the procedures we have that help cross-check the integrity of the results; these are all procedures I've personally done, at least 30 times (though they have evolved somewhat over time).
This post is only the info; I'll put my commentary on what these things imply in a follow-up post. The procedures are the same Wake County-wide, and most of them apply all across NC. I don't have direct knowledge of how absentee voting is processed (by-mail or early voting (one-stop)).
Staffing
Every polling place in NC has two judges and one Chief Judge assigned. These three people sign off on many things. At least one must be a registered Democrat and one a registered Republican (I'm unaffiliated so I always have one D and one R judge assigned).
There is also some number of assistants, I've had as few as 2 for sleepy elections and 10 or so for Presidential elections. They are not involved with the reconciliation procedures.
All of us must stay in one another's presence all day (from 5:45 AM when we arrive, until the last voter in line at 7:30 PM has voted and we have reconciled everything and packed everything up). There are a couple exceptions: bathroom breaks and processing curbside voters.
Equipment
All the non-security-sensitive supplies (booths, office supplies and such) are delivered to the polling place the week before election. The board issues the security-sensitive supplies to the Chief Judge, some on Saturday and some on Monday. This includes the unvoted ballots in boxes sealed with a signature sticker, blank Authorization To Vote (ATV) forms, poll books, and a laptop with the county's registered voter info.
The Chief Judge returns all this Tuesday night after the election. (Tamper resistance is described later. The short version: most everything is in packaging sealed with the signature of all 3 judges).
Setup and opening
We all meet Monday evening at the polling place and set up all the non-security-sensitive stuff. Tuesday morning, before the polls open at 6:30 AM, the three judges do these things: * Open up the ballot box, verify that all the compartments are empty, then lock it back up. * Put the tabulator on the ballot box, turn it on. * The tabulator prints on a cash-register-like tape, the total number of ballots scanned, and the totals for each race. We verify these are all 0 and sign the bottom of the tape, which stays attached.
Voting flow
There are some other flows (a Help Table for people with the wrong address, etc.) but most voters flow through like this: * Give name and address at Registration Table * Worker finds a sticker corresponding to that voter in the poll book, repeats back the name and address for the voter to confirm. * Sticker is put on a blank ATV form. The voter signs, worker initials. * Voter takes the ATV to the Ballot Table. Worker there takes the ATV. * The voter gets issued the type of ballot listed on the ATV (e.g. which NC Senate district? In a primary, which party?) and goes off to vote. * The worker sequentially numbers the ATV and puts it on a spindle. So the number on the top ATV will equal the number of ballots issued. * The voter marks up the ballot, feeds it into the tabulator, it gets scanned and dropped in the ballot box. A count on the tabulator screen increments. * Sticker issued, voter goes on about their day.
During the day, we periodically check that the top ATV number equals the number of scanned ballots on the tabulator screen, plus the number of people currently in booths marking ballots (a form assists). Discrepancies get investigated.
Closing the polls
The three judges do all this together:
We sign the top ATV.
We tell the tabulator to close polls. It prints the total count of ballots and the counts for each race. This tape is still attached to the zero tape. We sign the bottom and detach it. This double tape goes in a bag (sealed and signed by the 3 judges) and returned by the Chief Judge.
Two more results tapes are printed. Each goes into an envelope addressed to the Board of Elections, is given to one of the non-chief judges, and that judge mails it the next day.
Another results tape is printed. This is posted on the door of the polling place.
One last results tape is printed, it's left attached to the tabulator when it gets returned by the CJ.
We fill out this reconciliation form. The first section checks that the number of scanned ballots (plus any unscannable ones) equals the number of ATVs issued.
The ballots come in shrinkwrapped 100-packs. Any open ones left at the end of the day get counted. The number of unvoted ballots plus scanned and unscannable ballots plus provisional ballots (returned in envelopes) plus spoiled ballots (returned to the board in the same bag as the results tape) needs to equal the number of ballots issued to the CJ. That's on the other section of the reconciliation form.
The judges sign the reconciliation form. We pack up materials to return in some bags (issued ATVs and voted provisional ballots among them) in plastic bags that we seal and all 3 sign across the seal. A thumb drive from the tabulator goes in its own bag (new with the most recent tabulators).
We pack up the voted ballots into boxes (and unvoted ones into other boxes), all sign sticker seals and seal the boxes.
The Chief Judge takes everything they were issued back to the board, along with all those bags. Other stuff is left in a designated place for the moving company to pick up.