Observation foiled the plots - many thanks to Republican observers!
Solutions or at least some discussion points for around the water-cooler... [[ with good intentions from a non-american who lives in a representative democracy where a federal election department administers federal and state elections. ]]
Compulsory voting in Federal elections by all adult citizens. Payment for voting by electronic means: therefore a form of voter ID required to accept registration and payment.
If there are a known quantity of registered voters you then expect the total number of votes cast to numerically match up within a reasonable margin. This prevents “Snipes” votes - the extra extra catchup misplaced votes turning up inside all manner of trains planes and automobiles.