Many of the 48 states of the United States of America plus several of its territories and the District of Columbia issued individual passenger license plates for 1921.[1][2][3][4]
none| 12345 | | Alaska | First year for territory plates. State plates begin in 1959. |
| American Samoa Territory issued plates begin in 1924. |
| Arizona |
| Arkansas |
| California | Embossed black lettering and rims on yellow base. | none | unknown |
| Canal Zone | Embossed black on gray-green background | none | 1234 |
| Colorado | 123–456 |
| Connecticut | Embossed yellow numbers on black plate with border line; "CONN.–1921" embossed in yellow characters centered at bottom. | none | 12-345
123–456 | 1 to approximately 110-000 |
| Delaware |
| District of Columbia |
| Florida |
| Georgia |
| Guam |
| Hawaii Territory issued plates begin in 1922. State issued plates begin in 1959. |
| Idaho | Embossed black numbers on white plate with border line; "IDAHO 54" embossed in black block letters centered at bottom. | none | A 12345
0/A 12345 | Coded by county |
| Illinois | lettering and rims embossed on base; "ILL 21" embossed at right. | none | 123–456 | 1 to approximately ?? |
| Indiana | Black lettering embossed on orange base. | none | 123456 | County-coded |
| Iowa | Embossed silver lettering on black base; "IA 21" embossed at right. none. | 123456 |
| Kansas | Embossed black numbers on orange plate with border line; "KAN 21" embossed in black block letters at right. | none | 123456 | County-coded |
| Kentucky | Brown base with white embossed lettering and border. "KY. 1921" at right. | none | 123456 | Issued in blocks by county |
| Louisiana | 12345 |
| Maine | Embossed white lettering and rims on red base. "MAINE 1921" embossed at bottom center. | none | 12-345
123–456 (both with square dash) |
| Maryland | Embossed red numbers and rims on white plate; "MD 21" embossed at bottom center. | none | 123–456 |
| Massachusetts |
| Michigan | White embossed lettering on black base, stylized "MICH 21" at left. | none | 123–456 | Issued in front and rear pairs. |
| Minnesota | Embossed black lettering and rims on turquoise plate; "MINN" embossed vertically at right. | A123456 | "A" for weight class of vehicle. |
| Mississippi | White with embossed red lettering and rim. "1921" stamped vertically to left of registration number, "MISS" stamped vertically to right. | none | 12345 | unknown |
| Missouri | Embossed XX lettering and rims on XX base. "MO 1921" embossed at bottom. | none | 12-345 |
| Montana | Embossed XX numbers on XX base. | none |
| Nebraska | none |
| Nevada | none |
| New Hampshire | none | County-coded |
| New Jersey | Embossed white lettering on green base; "N. J. 21" embossed at top. | none | 123456 |
| New Mexico | none |
| New York | Embossed white lettering and rims on navy blue base; "NY 1921" embossed at bottom center. | none | 123–456 |
| North Carolina | Embossed white letters on brown base. | none | 123456 |
| North Dakota | none |
| Northern Mariana Islands Territory issued plates begin in 1944. |
| Ohio |
| Oklahoma | none |
| Oregon | Embossed white numbers on green plate. "ORE 1921" embossed at right. | none | 12345 |
| Pennsylvania | Embossed blue lettering on yellow base. "PENNA 1921" embossed at bottom with keystone logos on either side. | none | 1–234 |
| Puerto Rico |
| Rhode Island | none |
| South Carolina | none |
| South Dakota | Embossed white lettering on green base. | none | 123456 | 30000 to approximately 154000 | Numbers below 30000 reserved for motorcycles and trucks. |
| Tennessee | none | 12345 |
| Texas | 123–456 |
| Utah | Embossed yellow lettering and top and bottom border on black plate. "U 21" embossed at right. | none | 12345 |
| Vermont | Embossed dark green numbers on white plate; "54 VERMONT" embossed in dark green block letters centered at bottom. | none | 12345
A1234 |
| Virginia | Embossed dark blue lettering on orange plate. | none | 12345 |
| Washington | none |
| West Virginia | none | 12345 |
| Wisconsin | none |
| Wyoming | Embossed white numbers on black 1920 base plate; "1921 WYO" embossed in black-on-green metal insert at left. | none | 12345 |