 US @-@ 89 leaves Salt Lake City at exit 312 of I @-@ 15 , where it acts as I @-@ 15 's frontage roads . Just south of I @-@ 15 's junction with I @-@ 215 , US @-@ 89 splits to the northeast , passing through Bountiful and Woods Cross . A northerly curve onto 500 West removes the highway from Bountiful 's Main Street , and it merges with I @-@ 15 at exit 317 to bypass Centerville and Farmington , where the old road ( former US @-@ 91 , but never US @-@ 89 ) is SR @-@ 106 , through the narrow strip of land that separates Farmington Bay from the Wasatch Mountains . US @-@ 89 leaves I @-@ 15 at exit 324 , where the Legacy Parkway also ends , and proceeds north on a freeway . This portion of US @-@ 89 is the only one to include exit numbers based on its own mileage , as opposed to the overlapping I @-@ 15 or I @-@ 70 . The freeway ends after US @-@ 89 crosses SR @-@ 273 , the former surface alignment of US @-@ 91 in both directions , and heads north as a four @-@ lane road along the Wasatch foothills , to the east of Layton and Hill Air Force Base . After crossing I @-@ 84 in Uintah , US @-@ 89 enters Ogden , which it traverses via Washington Boulevard , rejoining old US @-@ 91 ( now SR @-@ 26 ) south of downtown . Beyond Ogden , US @-@ 89 continues in a general northerly direction along the thin strip between Willard Bay and the Wasatch Mountains to Brigham City , where it finally turns east away from the I @-@ 15 corridor . 
