The easiest way to reach the top of Mount Washington, the highest elevation in the northern Appalachians at more than 6,000 feet, is on the steep Cog Railway that has been carrying tourists since it opened, the first of its kind in the world, in 1869. On a clear day, the view from the summit of Mount Washington spans four states; on a cloudy day, you may be able to look down on the tops of clouds.