Here are the license number prefixes for the counties in Montana...
My wife and I have always loved looking at people's Montana license plates and trying to figure out where they are registered and from. The numbers used to be assigned based upon population but that is no longer accurate. Granted, with so many new vanity and speciality plates is getting harder to do! But here is a list I found at the Montana Association of Counties website. Have fun!
1
Butte/Anaconda
2
Great Falls/Cascade
3
Billings/Yellowstone
4
Missoula/Missoula
5
Helena/Lewis & Clark
6
Bozeman/Gallatin
7
Kalispell/Flathead
8
Lewiston/Fergus
9
Broadus/Powder River
10
Red Lodge/Carbon
11
Malta/Phillips
12
Havre/Hill
13
Hamilton/Ravalil
14
Miles City/Custer
15
Polson/Lake
16
Glendive/Dawson
17
Wolf Point/Roosevelt
18
Dillon/Beaverhead
19
Fort Benton/Chouteau
20
Glasgow/Valley
21
Shelby/Toole
22
Hardin/Big Horn
23
RoundUp/Musselshell
24
Chinook/Blaine
25
Virginia City/Madison
26
Conrad/Pondera
27
Sidney/Richland
28
Deer Lodge/Powell
29
Forsyth/Rosebud
30
Anaconda/Anaconda-Deer Lodge
31
Choteau/Teton
32
Columbus/Still Water
33
Hysham/Treasure
34
Plenty Wood/Sheridan
35
Thompson Falls/Sanders
36
Stanford/Judith Basin
37
Scobey/Daniels
38
Cut Bank/Glacier
39
Baker/Fallon
40
Big Timber/Sweet Grass
41
Circle/McCone
42
Ekalaka/Carter
43
Townsend/Broad Water
44
Harlowtown/Wheatland
45
Terry/Prairie
46
Philipsburg/Granite
47
White Sulphur Springs/Meagher
48
Chester/Liberty
49
Livingston/Park (Me!)
50
Jordan/Garfield
51
Boulder/Jefferson
52
Wibaux/Wibaux
53
Ryegate/Golden Valley
54
Superior/Mineral
55
Winnnet/Petroleum
56
Libby/Lincoln
And there you go!!
Here is a screen print of them for now, until I get the time to make a real document.
If I find the time, I will also do Idaho since they are a neighboring state. Not sure how many other neighboring states do the same thing.