The state highways in Montana are the state highways owned and maintained by the Montana Department of Transportation (MDT) in the US state of Montana.

Montana's state highways are classified as either primary or secondary.^[1] Several of Montana's state highways (both primary and secondary), or sections thereof, have also been designated as part of the National Highway System.^[1]

The square markers used today to identify primary Montana highways are only slightly different from their 1940s and earlier predecessors. The old markers used the word "ROUTE" above the number in big size, the route number in the middle, and the word "MONTANA" from edge-to-edge at the sign bottom.^[1] The font used was similar to that used for US routes.

More information Number, Length (mi) ...

Number	Length (mi)[2][3]	Length (km)	Southern or western terminus	Northern or eastern terminus	Formed	Removed	Notes
MT 1	—	—	US 191 near Grayling	US 10 near Sappington	—	—	Replaced by MT 287 (now US 287)
MT 1	63.652	102.438	I-90 in Opportunity	I-90 in Drummond	01922-01-011922	current
MT 2	63.241	101.777	I-90 in Butte	I-90 in Three Forks	—	—
MT 3	—	—	Idaho border near Heron	US 93 in Ravalli	—	—	Replaced by US 10 Alt
MT 3	221.770	356.904	I-90 in Billings	I-15 and US 89 in Great Falls	—	—
MT 4	24	39	Idaho state line	MT 3 in Thompson Falls	—	—	decommissioned when Idaho truncated SH 4 at Burke; Replaced by Forest Service Road NF-7623 (connects to Burke) and S-471
MT 5	65.573	105.530	MT 13 in Scobey	ND 5 in Westby	—	—
MT 6	—	—	US 10 Alternate in Townsend	US 10 in Forsyth	—	—	Replaced by US 12
MT 7	80.585	129.689	S-323 in Ekalaka	I-94 in Wibaux	01930-01-011930	current
MT 8	—	—	US 87 in Crow Agency	MT 22 near Olive	—	—	Replaced by US 212
MT 9	—	—	Lolo Pass	US 93 at Lolo	—	—	Replaced by S-412 (now US 12)
MT 11	—	—	US 89 in Vaughn	Alberta border at Sweetgrass	—	01932-01-011932	Replaced by US 91
MT 11	—	—	—	—	—	—
MT 13	112.507	181.062	MT 200 in Circle	Hwy 36 at the Saskatchewan border	—	—
MT 13W	5.797	9.329	US 2 in Wolf Point	MT 13 in Bridge Park	—	01994-01-011994	Replaced by MT 25
MT 14	—	—	US 10 at Glendive	North Dakota border at Fairview	—	—	Replaced by MT 16 and MT 23N (later MT 20; now MT 200)
MT 15	—	—	US 87 in Stanford	US 2 in Chester	—	—	Replaced by S-230 (now MT 80) and S-223
MT 16	152.371	245.217	I-94 Bus. in Glendive	Hwy 6 at the Saskatchewan border	—	—
MT 17	—	—	—	—	—	—	location unknown
MT 17	14.082	22.663	US 89 near Kennedy Creek	Hwy 6 at the Alberta border	—	—
MT 18	—	—	US 87 in Grass Range	US 10/MT 14 in Glendive	—	—	Replaced by MT 20 (now MT 200) and MT 20S (now MT 200S)
MT 19	—	—	US 10 in Big Timber	US 2/MT 39 in Malta	—	—	Replaced by US 191
MT 19	21.482	34.572	US 87 and MT 200 near Grass Range	US 191 near Roy	—	—
MT 20	—	—	US 10 in Bonner	US 89 near Great Falls	—	—	Replaced by MT 200
MT 21	—	—	US 10 in Columbus	MT 6 at Ryegate	—	—	Replaced by S-300 and S-306
MT 21	20.776	33.436	US 287 near Augusta	MT 200 in Simms	—	—
MT 22	—	—	Wyoming border at Alzada	Saskatchewan border at Port of Ophiem	—	—	Replaced by US 212, MT 59, S-341, and MT 24
MT 23	7.527	12.114	MT 16 and MT 200 near Sidney	ND 68 at the North Dakota border	—	—	From 1951 to 1958, continued west to Circle
MT 23N	—	—	—	North Dakota border at Fairview	—	—	Replaced by MT 20 (now MT 200)
MT 23S	—	—	—	ND 68 at the North Dakota border	—	—	Replaced by MT 23
MT 24	58	93	MT 37 at Jennings	US 2 in Marion	—	—
MT 24	134.098	215.810	MT 200 near Brockway	Hwy 2 at the Saskatchewan border	—	—
MT 24W	2.892	4.654	MT 24 south of Glasgow	US 2 in Glasgow	—	01994-01-011994	Replaced by MT 42
MT 25	—	—	US 87 in Billings	US 87 in Lewistown	—	—
MT 25	5.797	9.329	US 2 in Wolf Point	MT 13 in Bridge Park	01994-01-011994	current
MT 26	—	—	MT 3 in Trout Creek	US 2 in Kootenai National Forest	—	—
MT 27	—	—	MT 19 in Winifred	MT 29 in Big Sandy	—	—	Replaced by S-226
MT 28	46.734	75.211	MT 200 near Plains	US 93 in Elmo	01924-01-011924	current
MT 29	—	—	US 87/US 89 in Great Falls	Port of Wildhorse	—	—	Replaced by US 87
MT 30	—	—	US 12 near Miles City	South Dakota border near Mill Iron	—	—
MT 31	—	—	US 10 in Drummond	MT 35 near Bigfork	—	—	Replaced by S-271 and MT 83
MT 32	—	—	Yellowstone National Park at Silver Gate	US 310 at Rockvale	—	—	Replaced by US 212
MT 33	—	—	US 91/MT 20 in Wolf Creek	US 89 in Choteau	—	—	Replaced by US 287
MT 34	—	—	MT 41 in Twin Bridges	MT 287 in Ennis	—	—	Replaced by rerouted MT 287
MT 35	50.669	81.544	US 93 in Polson	US 2 in Evergreen	—	—
MT 36	—	—	US 93 near Gibbons Pass	US 91 in Dillon	—	—	Replaced by MT 43 and S-278
MT 37	67.048	107.903	US 2 in Libby	US 93 in Eureka	—	—
MT 38	53.835	86.639	US 93 in Grantsdale	MT 1 in Porters Corner	01924-01-011924	current	Skalkaho Highway
MT 39	—	—	Port of Morgan at the Saskatchewan border	Hysham	—	—	Replaced by MT 19 (later S-242) and S-245
MT 39	51.163	82.339	US 212 in Lame Deer	North of I-94 near Forsyth	01977-01-011977	current
MT 40	4.505	7.250	US 93 south of Whitefish	US 2 west of Columbia Falls	—	—
MT 41	54.512	87.729	I-15 Bus. in Dillon	MT 2 in Vendome Station	—	—
MT 42	—	—	—	—	—	—	location unknown
MT 42	2.892	4.654	MT 24 south of Glasgow	US 2 in Glasgow	01994-01-011994	current
MT 43	77.462	124.663	US 93 at Lost Trail Pass	I-15 near Divide	—	—	Last mile near western terminus with US 93 is in Idaho.
MT 44	—	—	—	—	—	—	location unknown
MT 44	28.390	45.689	US 93 north of Dupuyer	I-15 east of Valier	—	—
MT 45	—	—	MT 8 in Lame Deer	US 10 in Forsyth	—	—	Replaced by S-315 (now MT 39)
MT 46	—	—	—	—	—	—	location unknown
MT 47	31.437	50.593	I-90 in Hardin	I-94 east of Custer	—	—
MT 48	6.839	11.006	MT 1 near Anaconda	I-90 near Warm Springs	—	—
MT 49	—	—	—	—	—	—	location unknown
MT 49	11.734	18.884	US 2 in East Glacier Park	US 89 north of Kiowa	—	—
MT 50	—	—	MT 13 southeast of Wolf Point	US 2 east of Wolf Point	—	—	Replaced by MT 13
MT 50	—	—	Idaho border at Raynolds Pass	US 287 west of Hebgen Lake	—	—	Replaced by MT 87
MT 55	12.996	20.915	MT 41 north of Silver Star	I-90 at Whitehall	—	—
MT 56	34.646	55.757	MT 200 west of Noxon	US 2 east of Troy	01977-01-011977	current
MT 59	195.389	314.448	WYO 59 at the Wyoming border	MT 200 at Jordan	—	—
MT 64	9.039	14.547	Big Sky Resort	US 191 near Big Sky Resort	—	—
MT 66	50.022	80.503	US 191 south of Landusky	US 2 at Fort Belknap	—	—
MT 67	1.755	2.824	US 2 in Shelby	I-15 in Shelby	—	—
MT 68	1.494	2.404	I-15 south of Cascade	I-15 north of Cascade	—	—
MT 69	38.395	61.791	MT 55 at Whitehall	I-15 at Boulder	—	—
MT 72	21.408	34.453	WYO 120 at the Wyoming border	US 310 south of Bridger	01977-01-011977	current
MT 77	1.991	3.204	Hot Springs	MT 28 east of Hot Springs	01977-01-011977	current
MT 78	47.714	76.788	US 212 at Red Lodge	I-90 at Columbus	01977-01-011977	current
MT 80	67.172	108.103	US 87 at Stanford	US 87 at Fort Benton	—	—
MT 81	42.446	68.310	MT 80 near Coffee Creek	US 191 at Brooks	—	—
MT 82	6.862	11.043	US 93 north of Somers	MT 35 north of Bigfork	01977-01-011977	current
MT 83	91.118	146.640	MT 200 at Clearwater Junction	MT 35 north of Bigfork	01977-01-011977	current
MT 84	28.904	46.516	US 287 in Norris	US 191/MT 85 near Four Corners	—	—
MT 85	6.704	10.789	US 191/MT 84 near Four Corners	I-90 at Belgrade	—	—
MT 86	37.498	60.347	US 191/I-90 Bus. in Bozeman	US 89 near Wilsall	—	—
MT 87	8.571	13.794	SH 87 at the Idaho border	US 287 west of Quake Lake	01987-01-011987	current
MT 110	—	—	US 10 near Opportunity	US 10 in Drummond	—	—	Replaced by US 10 Alternate
MT 117	13.138	21.144	MT 24 at Fort Peck	US 2 at Nashua	—	—
MT 135	21.549	34.680	I-90 at St. Regis	MT 200 near Paradise	01977-01-011977	current
MT 141	32.468	52.252	US 12 at Avon	MT 200 north of Helmville	01977-01-011977	current
MT 187	—	—	US 10 in Bozeman	US 89 in Wilsall	—	—	Replaced by S-293 (now MT 86)
MT 191	—	—	US 191 near Grayling	US 10 near Sappington	—	—	Replaced by MT 1 (later MT 287, now US 287)
MT 200	706.624	1,137.201	SH 200 at the Idaho border east of Cabinet, Idaho	ND 200 at Fairview	01967-01-011967	current	Longest state highway in Montana
MT 287	48.822	78.571	MT 41 at Twin Bridges	US 287 at Ennis	—	—
MT 789	—	—	Wyoming border south of Warren	Alberta border at Sweetgrass	—	—	Part of US 789 corridor

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Montana's secondary system was established in 1942,^[4] but secondary highways (S routes) were not signed until the 1960s.^[1] S route designations first appeared on the state highway map in 1960^[5] and are abbreviated as "S-nnn". Route numbers 201 and higher are, with very few exceptions, exclusively reserved for S routes. Notable exceptions include, MT 287, and the former MT 789.

The highway markers for Montana's Secondary Highways are distinctive in that the route number appears in black on a white down-pointing arrowhead.^[1] (Early markers were white numbers on black arrowheads with the word Montana in the flat top of the inverted arrowhead and Secondary appearing below the route number on the shields.)

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