The widest point of Maryland occurs at its northern border with Pennsylvania. The measured width there is about 250 miles.
At 2.3 miles, 14th Street is the widest point in Manhattan.
The widest country from East to West is Russia at 9,000 km (5,592 miles)
Madagascar is about 400 kilometers or 250 miles wide at it's widest point. Madagascar is also about 1600 kilometers or 1000 miles long.
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.
47 miles
Its about 1 3/4s mile at its widest point (got answer out of my schools science book)
Google Maps says 358 miles from Jacksonville, FL to Pensacola, FL. Add another 10 miles or so to get to the Alabama line, and you're around 370 road miles. Google Earth shows it as 360 miles "as the crow flies", so those numbers agree nicely.
Lake Ontario is the furthest east. In addition, it is the smallest lake, only 53 miles across at its very 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 England is 302 miles at its widest point.
The longest crosstown (east-west) street in Manhattan is 14th Street. At 2.3 miles (3.7 km), it is the widest point of Manhattan.
At its widest point, Tasmania is about 300 km from east to west.