47 miles
Hawaii is the widest state east to west.
Several sources found on the internet, among them the Hawaii state tourist board, Yahoo, and the US States Almanac, all agree that Hawaii is the widest state on an east-west axis. However, as the global divisional point between east and west is 180° longitude. And that Alaska spans across the 180° longitude line; if you are to measure FROM the "eastern" most point of Alaska (at 180° longitude) TO the "western" most point of Alaska (also at 180° longitude) at approximate the 50th parallel; then you have a measurement of approximated 17,000 miles -- clearly making Alaska the widest state as measured FROM east TO west.
The widest country from East to West is Russia at 9,000 km (5,592 miles)
At 2.3 miles, 14th Street is the widest point in Manhattan.
The widest point in Britain from west to east is approximately 874 miles (1,407 kilometers) between the easternmost point of East Anglia and the westernmost point of Ardnamurchan in Scotland.
At its widest point, Tasmania is about 300 km from east to west.
From the East Coast to the West Coast the U.S. is roughly 3000 miles long. Its nearly 3400 from the widest part
Pennsylvania
At its widest point from east to west, Tasmania spans 315 km.
Massachusetts is 190 miles long and 50 miles wide at its widest point
It is 962 km (598 mi) North to South at it's tallest point and 950 km (590 mi) East to West at it's widest point.
The widest distance across the US is between West Quoddy Head, Maine, and Cape Alava, Washington. The distance is 14,232,648.413 feet. This is equal to 3,481,811,123.62824 cm.