In cases when the year of publication was not shown on the cover or in the legend, map companies put date codes at the bottom of the main map. The table below shows the codes for two main map producers, Rand McNally and H.M. Gousha. While Rand McNally always used the first letter or first one or two digits of a code to indicate the year, the year letter could appear anywhere in the Gousha code, so other clues (census date, road network) may be necessary to verify it. Rand McNally first used date codes in 1919, and Gousha started in 1927.
Year | Rand McNally | H.M. Gousha | Year | Rand McNally | H.M. Gousha | Year | Rand McNally | H.M. Gousha | ||
---|---|---|---|---|---|---|---|---|---|---|
1919 | A | – | 1949 | 9 | W | 1979 | 79 | AB | ||
1920 | B | – | 1950 | 0 | X | 1980 | 80 | AC | ||
1921 | C | – | 1951 | 1 | Y | 1981 | 81 | AN | ||
1922 | D | – | 1952 | 2 | Z | 1982 | 82 | MZ | ||
1923 | E | – | 1953 | 3 | AA | 1983 | 83 | OB | ||
1924 | F | – | 1954 | 4 | BB | 1984 | 84 | YL | ||
1925 | G | – | 1955 | 5 | CC | 1985 | 85 | CP | ||
1926 | H | – | 1956 | 6 | DD | 1986 | 86 | KX | ||
1927 | I | A | 1957 | 7 | EE | 1987 | 87 | QD | ||
1928 | J | B | 1958 | 8 | FF | 1988 | 88 | WJ | ||
1929 | K | C | 1959 | 9 | GG | 1989 | 89 | ER | ||
1930 | L | D | 1960 | 0 | HH | 1990 | 90 | IV | ||
1931 | M | E | 1961 | 1 | II | 1991 | 91 | SF | ||
1932 | N | F | 1962 | 2 | JJ | 1992 | 92 | UH | ||
1933 | O | G | 1963 | 3 | KK | 1993 | 93 | GT | ||
1934 | P | H | 1964 | 4 | LL | 1994 | 94 | NA | ||
1935 | Q | I | 1965 | 5 | MM | 1995 | 95 | ZM | ||
1936 | R | J | 1966 | 66 | NN | 1996 | 96 | BO | ||
1937 | S | K | 1967 | 67 | OO | 1997 | 97 | – | ||
1938 | T | L | 1968 | 68 | PP | 1998 | 98 | – | ||
1939 | U | M | 1969 | 69 | 1999 | 99 | – | |||
1940 | V | N | 1970 | 70 | RR | 2000 | 00 | – | ||
1941 | W | O | 1971 | 71 | SS | 2001 | 01 | – | ||
1942 | X | P | 1972 | 72 | TT | 2002 | 02 | – | ||
1943 | Y | Q | 1973 | 73 | UU | 2003 | 03 | – | ||
1944 | Z | R | 1974 | 74 | VV | 2004 | 04 | – | ||
1945 | 5 | S | 1975 | 75 | WW | 2005 | 05 | – | ||
1946 | 6 | T | 1976 | 76 | XX | 2006 | 06 | – | ||
1947 | 7 | U | 1977 | 77 | YY | 2007 | 07 | – | ||
1948 | 8 | V | 1978 | 78 | ZZ | 2008 | 08 | – |
Stan DeOrsey has provided a more detailed explanation of how Rand McNally dates their maps.