How many letters does the top answer for “a state of north central united states bordering on canada” have?

The most common answer is nd (2 letters).

Crossword clue: a state of north central united states bordering on canada

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

nd 2 letters wn-def

a state of north central United States bordering on Canada

a state in north central united states 67% similar → sd

a midwestern state in north central united states 57% similar → wi, wisconsin

the north central region of the united states 57% similar → midwest