The U.S. state closest in size to England in terms of square miles is Alabama. The total land area of England is slightly more than 50,500 square miles. Alabama is only slightly larger at 50,700 square miles in size.
Most size comparisons, however, include the entire United Kingdom (England, Scotland, Wales and Northern Ireland). Official U.S. documents issued for diplomatic purposes name Oregon as the U.S. state closest in size to the United Kingdom, though a review of the total square miles of the entire United States reveals that there is actually less difference in terms of square miles between Wyoming and the United Kingdom than Oregon and the United Kingdom.
In its entirety, the United Kingdom is about 94,000 square miles in size. Oregon is just under 96,000 square miles. Wyoming is just over 93,000 square miles, which makes the difference in square miles less between Wyoming and the United Kingdom.