Interstate 90 in Montana

Interstate 90
Interstate 90
	I-90 highlighted in red
Route information
	Maintained by MDT
Length	552.46 mi (889.10 km)
Existed	1957–present
History	Completed in 1987
NHS	Entire route
Major junctions
West end	I-90 at Idaho state line
	US 93 / MT 200 in Missoula; US 12 from Missoula to Garrison; I-15 west of Butte; I-115 in Butte; I-15 east of Butte; US 191 in Bozeman; US 212 / US 310 in Laurel; US 87 in Billings; I-94 in Billings; US 212 near Crow Agency;
East end	I-90 / US 87 at Wyoming state line
Location
Country	United States
State	Montana
Counties	Mineral, Missoula, Granite, Powell, Deer Lodge, Silver Bow, Jefferson, Broadwater, Gallatin, Park, Sweet Grass, Stillwater, Yellowstone, Big Horn
Highway system
	Interstate Highway System; Main; Auxiliary; Suffixed; Business; Future; Montana Highway System; Interstate; US; State; Secondary;

Interstate 90 (I-90) is an east–west transcontinental Interstate Highway across the northern United States, linking Seattle to Boston. The portion in the state of Montana is 552.54 miles (889.23 km) in length, passing through 14 counties in central and southern Montana. It is the longest segment of I-90 within a single state.^[2]

^ Starks, Edward (January 27, 2022). "Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved September 16, 2022.
^ Rand McNally (2023). "United States" (Map). Rand McNally Road Atlas: United States (2024 ed.). 1:9,820,800. Chicago: Rand McNally. pp. 2–3. ISBN 978-0-528-02718-5.

[table1-1] Starks, Edward (January 27, 2022). "Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved September 16, 2022.

[2] Rand McNally (2023). "United States" (Map). Rand McNally Road Atlas: United States (2024 ed.). 1:9,820,800. Chicago: Rand McNally. pp. 2–3. ISBN 978-0-528-02718-5.

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