Tibble Fork turn off. From midway between Salt Lake City and Provo on I-15, take exit 287, which is the Alpine-Highland/US 92/Timpanogos National Monument/Cabella's exit. Drive about 7.5 miles east on HWY 92 to the mouth of the canyon. Continue up the canyon (fee area $6 for a 3 day pass, $50 for year) for about 5 miles to where the road forks and the North and South Forks of the American Fork meet.