From Bergen County, NJ, USA to Zion National Park in Utah is the furthest I got as the crow flies. About 2,100 miles or 3,350 kilometers.
In terms of driving it’s the North Rim of the Grand Canyon which is about 35 hours of driving, 2,450 miles or 4000 kilometers.
In one day Estes Park, CO to around Topeka, KS which is about 600 miles or about 950 kilometers.