From Salt Lake point your vehicle south on I-15 and just keep on driving. Along the way you'll skirt the eastern shores of Utah Lake and Mona Reservoir, and follow along the western fringes of Fishlake National Forest. Just beyond Cedar City, at Exit 40, you can access the park's northern section via Kolob Canyon Road. Or you can continue south to Exit 27 and follow Route 17 into Route 9 which will directly lead you into the park's main showcase, Zion Canyon.
For a more scenic approach take Exit 222, just south of the town of Nephi (about an hour south of Salt Lake) and veer onto Route 28. Follow it south. Just after passing I-70 the route becomes 89. This scenic valley road mirrors the Sevier River while passing Mount Belknap and Delano Peak, both over 12,000 feet. It also scoots past Route 12, the turnoff for Bryce National Park. Travel as far as Mount Carmel Junction and turn right (west) on Route 9. Follow for 12 miles into Zion via the park's eastern entrance.