From January or February 1861 until July, Judah and Strong led a 10-person expedition to survey the route for the railroad over the Sierra Nevada through Clipper Gap and [[Emigrant Gap]], over [[Donner Pass]], and south to [[Truckee, California|Truckee]]. They discovered a way across the Sierras that was gradual enough to be made suitable for a railroad, although it still needed a lot of work.