I-84 climbs Emigrant Hill, a 6% grade, into the Blue Mountains. The westbound lanes switchback twice on its descent into Pendleton. Eastbound lanes feature the tightest curves allowed on the Interstate Highway system, even though those curves are on the uphill (eastbound) direction. This grade is also well known because of the distance between eastbound and westbound lanes, nearly between the opposite directions of travel at some points. The road summits at above sea level before descending to the Grand Ronde River and La Grande. It passes by North Powder and Baker City and through the Burnt River canyon. Around Huntington, it crosses into the Mountain Time Zone then briefly follows the southwest bank of the Snake River (Brownlee Reservoir), then continues to Ontario before crossing the Snake River into Idaho. On March 1, 2016, the speed limit from The Dalles to Ontario was raised to , while the truck speed was raised to . Idaho I-84 enters Idaho by crossing the Snake River at Ontario, Oregon. From there, it continues on to the major cities of the Treasure Valley (or Boise metropolitan area) including Caldwell, Nampa, Meridian, and Boise (where I-184 connects travelers to downtown). From Boise, I-84 continues southeast passing near several small cities (Mountain Home, Glenns Ferry, and Jerome) on its way to Twin Falls. Just east of Jerome, I-84 passes within of Twin Falls, but does not cross the Snake River Canyon or into Twin Falls County. Access to Twin Falls is afforded by an intersection with US 93 at Exit 173; US 93 southbound crosses the Snake River via the Perrine Bridge. After Twin Falls, I-84 continues through Burley and Heyburn. Approximately east of Declo in rural Cassia County, I-84 meets the western terminus of the western section of I-86. While I-86, along with US 30 heads east, then northeast to American Falls and Pocatello (following the Oregon Trail), I-84 heads southeast to the border with Utah. In 2014, the speed limit on rural sections of I-84 in Idaho was raised to . Utah From Idaho, I-84 enters Utah at a point approximately 7 miles (11.3 km) from Snowville in Box Elder County. It proceeds southeast through Rattle Snake Pass towards Brigham City where I-84 joins I-15 (just west of Tremonton) for its next . Just north of Brigham City, at Corinne, Utah, I-84 joins the route of the First transcontinental railroad which the highway