An initial count of millions of ballots can finish in a night, while a recount of the same ballots takes weeks. The difference is procedure rather than arithmetic.
The first count is machine tabulation
Most American jurisdictions tabulate by scanning ballots, with equipment reading marks at high speed and aggregating totals by precinct.
Machines handle volume well and are not the bottleneck. Election night results are essentially the output of that scanning plus the reporting chain that moves numbers upward.
What machines cannot do is resolve ambiguity. A mark that does not meet the reading threshold is set aside rather than interpreted.
A recount is a legal proceeding
Recounts operate under statutes that specify who may request one, under what margin, at whose expense and by what method. The rules differ by state and sometimes by contest.
Once triggered, the process runs with representatives of the campaigns present, along with observers and often the press. Each has standing to raise objections.
Every objection is logged and resolved, and resolution takes time even when the disputed ballot count is small.
Ballots are examined individually
Where a hand recount is used, teams review ballots one at a time, applying the state's voter-intent standard to marks a scanner would have rejected.
Teams are usually bipartisan by design, and disagreement escalates to a canvassing board rather than being settled at the table.
That escalation path is the point. It creates a record showing how each contested ballot was decided, which is what makes the result defensible afterward.
Chain of custody governs movement
Ballots are sealed, logged and stored under rules that dictate who may open a container and in whose presence. Opening a sealed box is itself a documented event.
Each of those steps has to be performed in order, with signatures. The paperwork exists so that the physical handling can be reconstructed later if challenged.
Speed is deliberately not the objective here. The procedure trades throughput for auditability.
Litigation runs in parallel
Disputes about which ballots are eligible for review, or how a standard should be applied, frequently move to court while the count continues.
Courts set their own timelines, and a ruling can require revisiting work already completed. That possibility keeps parts of the process provisional until deadlines pass.
State certification deadlines eventually close the window regardless, which is why recount schedules read as a race against a statutory date rather than a search for a finish line.