The most important road in the county is Interstate 15, which runs north-south through the center of the county. US-89 enters parallel to I-15 from Salt Lake County to the south and runs north through North Salt Lake and Bountiful as a city road before merging with I-15. It re-emerges in Farmington near the Lagoon Amusement Park, heading along the eastern benches on the slopes of the Wasatch Range, entering Weber County near South Weber. The Utah Department of Transportation is currently (2019) upgrading US-89 to a freeway through eastern Layton north to its interchange with I-84 near the Weber County border. Congestion is a significant problem in the county, as east-west transportation is restricted by the narrow urban corridor and many of its citizens commute south to Salt Lake County.