Well, the two states share a border, so technically there is very little distance between them. Assuming, however, that you mean the distance between two places in each state, that depends on where...
167.54 kilometres (104.1 miles)
20 miles taking U.S. 30 WEST.
5,424.96 kilometres (3,370.92 miles) from York, England to New York City.
425.15 kilometres (264.18 miles)