In 1950 Indiana established County Codes for Car Plates which were designated by 2 letters followed by up to 4 numbers.
So for each pair of letters there would be a maximum of 9,999 plates. A county with less than 9,999 Cars would only need 1 pair of letters.
The system was based on the County with the Largest Number of Registered Autos starting with the letters AA and using as many pairs of letters as needed for their Automobiles.
The 2nd County would start with BB, the 3rd would start with CC and so on.
After a decade of using this system the combinations of Pairs of Letters were running out and the system was getting confusing jumping around in the alphabet to create codes.
There are notes mentioning the letters US being used at Grissom Air Force Base in Miami County and possibly Fort Benjamin Harrison in Indianapolis.
I have also seen charts where RP stood for Republican Party. Since the BMV was always a Political Factor in the State, this could be true.
In 1963 the “1 thru 92” Alphabetized system was established. 1 for Adams, 2 for Allen and 92 for Whitley County.
Following the number of the county was a single letter (typically standing for the BMV Branch within the county) and a possible 9,999 plates per County Number and Branch Letter. Now every County could have as many as 260,000 plates.
It is well known, and still seen today, letters “D” and “R” were used to designate Democrat and Republican. This can be seen in Smaller Counties only needing less than 30,000 plates and they used “A”, “B” and “C”. So why do they have a few plates with “D” and “R” ? So Political Affiliations can be clearly seen in this manner.
Soon after this system was started Marion County needed additional Numbers so 93 was used so another 260,000 numbers were available,
Then Lake County used 94. Marion County then used 95, Lake County then used 96. Marion rounded off the 97,98 and 99.
Now this system was used up. There was even some double letter used in Allen County for a few years.
Not until versions of letters and numbers seen today would there be enough combinations to suffice.
This is a Cross-Reference between the 1950-1962 system and 1963 system for easy reference.
Indiana County Codes
1 Adams JA-JC
2 Allen DD-DN
3 Bartholomew ZA-ZB
4 Benton ND-NF
5 Blackford ZD-ZE
6 Boone HA-HB
7 Brown YE
8 Carroll QC
9 Cass SS-ST
10 Clark WA-WC
11 Clay FA-FB
12 Clinton XA-XB
13 Crawford ZG
14 Daviess XG-XH
15 Dearborn SG-SH
16 Decatur LC
17 DeKalb UA-UC
18 Delaware JJ-JW
19 Dubois PF
20 Elkhart GG-GM, JG
21 Fayette ZC
22 Floyd WW-WX
23 Fountain XJ-XL
24 Franklin TD
25 Fulton TC
26 Gibson NA
27 Grant NH-NR
28 Greene MA-MC
29 Hamilton SA-SB
30 Hancock UD, UF
31 Harrison XD
32 Hendricks EA-EC
33 Henry QP-QS
34 Howard PP-PW, PZ
35 Huntington UT-UV
36 Jackson SJ-SL
37 Jasper GF
38 Jay LA-LB
39 Jefferson EJ
40 Jennings LD
41 Joihnson KA-KC
42 Knox TS-TU
43 Kosciusko RM, RR-RT
44 Lagrange YD
45 Lake CA-CZ
46 La Porte LL-LP
47 Lawrence QA-QB
48 Madison FF-FL, FN
49 Marion AA-BA, BM, BR-BY
50 Marshall YA-YB
51 Martin FM
52 Miami ZX-ZZ, US
53 Monroe VV-VY
54 Montgomery TA
55 Morgan WF-WG
56 Newton ME-MF
57 Noble PA-PC
58 Ohio XE
59 Orange SE
60 Owen KN
61 Parke UE
62 Perry PY
63 Pike QD
64 Porter XX-XY
65 Posey HC-HD
66 Pulaski RD
67 Putnam NC
68 Randolph YX-YZ
69 Ripley SC-SD
70 Rush VE-VF
71 St. Joseph BB-BL, BN
72 Scott JD
73 Shelby RA-RC
74 Spencer SP
75 Starke VJ-VK
76 Steuben SU
77 Sullivan YF-YH
78 Switzerland GD
79 Tippecanoe MM-MR
80 Tipton DC
81 Union ED
82 Vanderburgh EE-EH, EK-EM
83 Vermillion FC-FD
84 Vigo HH-HL
85 Wabash VA-VB
86 Warren HE-HF
87 Warrick JF
88 Washington WD
89 Wayne KJ-KM
90 Wells GB-GC
91 White MG-MH
92 Whitley DA-DB
93 Marion
94 Lake
95 Marion
96 Lake
97 Marion
98 Marion
99 Marion
AA-BA MARION
BB-BK ST. JOSEPH
BM MARION
BN ST. JOSEPH
BR MARION
BU MARION
BX-BZ MARION
CA-CB DEARBORN
CC-CZ LAKE
DA-DB WHITLEY
DC TIPTON
DD-DN ALLEN
EA-EC HENDRICKS
ED UNION
EE-EH VANDERBURGH
EJ JEFFERSON
EK-EM VANDERBURGH
FA-FB CLAY
FC-FD VERMILLION
FF-FL MADISON
FM MARTIN
FN MADISON
GB-GC WELLS
GD SWITZERLAND
GF JASPER
GG-GM ELKHART
HA-HB BOONE
HC-HD POSEY
HE-HF WARREN
HH-HM VIGO
JA-JC ADAMS
JD SCOTT
JF WARRICK
JJ-JN DELAWARE
KA-KC JOHNSON
KG-KM WAYNE
KN OWEN
LA-LB JAY
LC DECATUR
LD JENNINGS
LL-LP LA PORTE
MA-MC GREENE
ME-MF NEWTON
MG-MH WHITE
MM-MQ TIPPECANOE
NA-NB GIBSON
NC PUTNAM
ND-NF BENTON
NH GRANT
NN-NP GRANT
NR GRANT
PA-PC NOBLE
PF DUBOIS
PP-PW HOWARD
PY PERRY
PZ HOWARD
QA-QB LAWRENCE
QC CARROLL
QD PIKE
QE LAWRENCE
QP-QS HENRY
RA-RC SHELBY
RD PULASKI
RM KOSCIUSKO
RR-RT KOSCIUSKO
SA-SB HAMILTON
SC-SD RIPLEY
SE ORANGE
SG-SH DEARBORN
SJ-SL JACKSON
SN HAMILTON
SP-SQ SPENCER
SS-ST CASS
SU STEUBEN
TA-TB MONTGOMERY
TC FULTON
TD FRANKLIN
TE FULTON
TS-TU KNOX
TW KNOX
UA-UC DE KALB
UD HANCOCK
UE PARKE
UF HANCOCK
US MIAMI, Grissom Air Force Base
UT-UV HUNTINGTON
VA-VB WABASH
VE-VF RUSH
VJ-VK STARKE
VV-VW MONROE
VY MONROE
WA-WC CLARK
WD WASHINGTON
WE CLARK
WF-WG MORGAN
WW-WX FLOYD
XA-XB CLINTON
XD HARRISON
XE OHIO
XG-XH DAVIEES
XJ-XL FOUNTAIN
XV PORTER
XX-XY PORTER
YA-YB MARSHALL
YD LAGRANGE
YE BROWN
YF-YH SULLIVAN
YX-YZ RANDOLPH
ZA-ZB BARTHOLOMEW
ZC FAYETTE
ZD-ZE BLACKFORD
ZF BARTHOLOMEW
ZG CRAWFORD
ZX-ZZ MIAMI
