Question: What mountains range does the high mountain pass through at an elevation of 6820 ft that has part of the Interstate Highway System that runs from San Diego, California, to Sweetgrass, Montana ?

Context paragraphs:
List of gaps in Interstate Highways: There are gaps in the Interstate Highway system, where the roadway carrying an Interstate shield does not conform to the standards set by the Federal Highway Administration (FHWA), the body that sets the regulations for the Interstate Highway System.  For the most part, the Interstate Highway System in the United States is a connected system, with most freeways completed; however, some Interstates still have gaps.  These gaps can be due to unconnected segments of the same route or from failure of the road to fully conform to Interstate standards by including such things as at-grade crossings, traffic lights, undivided or narrow freeways, or movable bridges (lift bridges and drawbridges).  This article deals with present-day gaps, as such examples were far more numerous during construction of the Interstate Highway System and the upgrading of existing roads to meet these standards, which did not occur everywhere at the same time.  Temporary gaps, such as lane closures that reduce traffic to one lane and reduce speed limits, are also excluded.

Blue Mountain Pass: Blue Mountain Pass is a high mountain pass in Oregon, United States that is traversed by U.S. Highway 95.  It gets its name from Blue Mountain (elevation 7435), which is just west of the pass.  Blue Mountain and Blue Mountain Pass are located in south eastern Oregon, approximately 25 miles north of the Nevada border.  They are not a part of the similarly named Blue Mountains of north eastern Oregon.

Interstate 85 in Virginia: Interstate 85 (I-85) is a part of the Interstate Highway System that runs from Montgomery, Alabama to Petersburg, Virginia.  In Virginia, the Interstate Highway runs 68.64 mi from the North Carolina state line near Bracey north to I-95 in Petersburg.  I-85 passes through the eastern part of Southside Virginia, where it parallels U.S. Route 1 (US 1) from Petersburg, where the highway runs concurrently with US 460, to south of South Hill, where the highway intersects Southside's major east–west highway, US 58.  The Interstate Highway is the primary connection between the Richmond–Petersburg metropolitan area and the Research Triangle and other major metropolitan areas of North Carolina.  Like all mainline Interstate Highways, I-85 is a part of the National Highway System for its entire length in Virginia.

Interstate 15 in Idaho: Interstate 15 (I-15) is a part of the Interstate Highway System that runs from San Diego, California, to Sweetgrass, Montana.  In Idaho, the Interstate Highway runs exactly 196 mi from the Utah state line near Woodruff north to the Montana state line at Monida Pass.  I-15 is the primary north–south highway of Eastern Idaho.  The Interstate Highway connects Pocatello and Idaho Falls, the fourth and fifth largest cities in Idaho, and the smaller county seats of Malad City, Blackfoot, and Dubois.  I-15 connects all of those cities with Salt Lake City to the south and Butte to the north.  The Interstate has business loops through McCammon, Inkom, Pocatello, Blackfoot, and Idaho Falls.

1962 Utah state route renumbering: Coinciding with the designation of several routes in the Interstate Highway System through Utah, the Utah State Legislature made several changes to the Utah State Route system.  The bulk of these changes were not visible to the public, but were to unsigned legislative designations only.  The primary effect was designating route numbers 1 through 5 for future corridors of the Interstate Highways in Utah.  There were also changes made to a few unsigned highways serving state parks and institutions.  Several other routes were truncated or re-assigned or split into multiple designations to allow the Interstate Highway corridors to have a single route number assigned.  As very little of the Interstate Highway System had been constructed in Utah by 1962, these changes were primarily to support future construction.  There were a number of cases where the legislative change enacted in 1962 would not be built and signed until years later.  Few of the changes made in 1962 are still valid today.  As construction of the Interstate Highway system proceeded, additional changes were made.  The legislature made a larger change in route designations in 1977, eliminating unsigned legislative and concurrences in the process.

Eisenhower Tunnel: The Eisenhower Tunnel, officially the Eisenhower–Edwin C. Johnson Memorial Tunnel, is a dual-bore, four-lane vehicular tunnel approximately 60 mi west of Denver, Colorado, United States.  The tunnel carries Interstate 70 under the Continental Divide in the Rocky Mountains.  With a maximum elevation of 11158 ft AMSL, it is one of the highest vehicular tunnels in the world.  The tunnel is the longest mountain tunnel and highest point on the Interstate Highway System.  Completed in 1979, it was one of the last major pieces of the Interstate Highway system to be completed.  The westbound bore is named after Dwight D. Eisenhower, the U.S. President for whom the Interstate system is also named.  The eastbound bore is named for Edwin C. Johnson, a governor and U.S. Senator who lobbied for an Interstate Highway to be built across Colorado.

Lemhi Pass: Lemhi Pass is a high mountain pass in the Beaverhead Mountains, part of the Bitterroot Range in the Rocky Mountains and within Salmon-Challis National Forest.  The pass lies on the Montana-Idaho border on the continental divide, at an elevation of 7373 feet above sea level.  It is accessed via Lemhi Pass Road in Montana, and the Lewis and Clark Highway in Idaho, both dirt roads.  Warm Springs Road, which roughly follows the divide in Montana, passes just west of the pass's high point.

Monida Pass: Monida Pass is a high mountain pass in the Rocky Mountains of the northwestern United States, at an elevation of 6820 ft (2079 m) above sea level on the Union Pacific Railroad and 6870 ft (2094 m) on adjacent Interstate 15.

Elk Park Pass: Elk Park Pass, elevation 6352 ft , is a mountain pass on the Continental Divide in southwestern Montana, about 4 mi northeast of Butte.  It is traversed by Interstate 15 and is one of three crossings of the Divide by the Interstate (all in Montana), the others being Monida Pass (on the border with Idaho) and Deer Lodge Pass southwest of Butte.  Elk Park Pass lies on the border between Silver Bow and Jefferson counties and is remarkable for its highly asymmetrical nature.  The approach from the north is through namesake Elk Park, a high, mostly treeless plain (like South Park in Colorado or the Sierra Valley in California), and the grade is almost imperceptible.  The elevation at the northeast end of the park, about 10 mi from the pass, is about 6200 ft , only 152 ft lower than the pass itself.  However, at the south end, the highway drops 750 ft from the pass into Butte over a distance of only about 4 mi .

Interstate 296: Interstate 296 (I-296) is a part of the Interstate Highway System in the US state of Michigan.  It is a state trunkline highway that runs for 3.43 mi entirely within the Grand Rapids area.  Its termini are I-96 on the north side of Grand Rapids in Walker and I-196 near downtown Grand Rapids.  For most of its length, the Interstate is concurrent with U.S. Highway 131 (US 131), which continues as a freeway built to Interstate Highway standards north and south of the shorter I-296.  The highway was first proposed in the late 1950s and opened in December 1962, but the Michigan Department of Transportation (MDOT) has since eliminated all signage for I-296 and removed the designation from their official state map.  The designation is therefore unsigned, but still listed on the Interstate Highway System route log maintained by the Federal Highway Administration (FHWA).

Supporting paragraphs: Interstate 15 in Idaho Monida Pass
Answer: Rocky Mountains