Classification of early baseball card sets is based on the categories found in the American Card Catalog (ACC). Although the scope of the ACC includes a wide range of cards featuring non-baseball subjects, the following categories are limited to only those that include baseball card sets.
B "Blankets" and cloth-like cards
C Canadian tobacco (Imperial Tobacco, C46, is the only baseball set)
D Bakery sets.
E Early gum and candy cards; "E" cards fall primarily into two time periods: 1909-1915 (designated here as Group "E1") and 1920-1927 (Group "E2")
F "Food" cards. Includes cards used to promote a wide range of foods ranging from breakfast cereals to ice cream
H Clothing and sporting goods manufacturers and retailers
M Inserts and promotions for magazines and newspapers
N Nineteenth century cards
P Pins (includes PD "bakery button inserts;" PE "button inserts with early candy or gum;" PM "miscellaneous inserts" as defined in the Sports Collectors Bible; PR "button inserts with recent candy and gum;" and PX "other novelties of plastic, metal, etc.")
R Candy, gum and some other cards of the 1930's and 1940's (beginning in 1928; generally, these are a continuation of the "E2" cards)
S Stamps and "silks"
T 20th century tobacco cards; a one digit number, such as T3, indicates an oversized premium or cabinet card. The baseball tobacco card era spanned a seven year period--from 1909 to 1915. One set from 1919 (Coupon Cigarettes T213-3) and several 1950s Redman tobacco sets (T232-T235) are also listed in the ACC as baseball "T" cards.
V Canadian candy and gum cards. Roughly, the Canadian equivalent of some of the American "E" and "R" cards
W Miscellaneous section (mostly, whatever doesn't fit above). "W" cards include anonymous issues, cards from games, strip cards, and a long series of sets produced by the Exhibit Supply Company of Chicago.
WG Game Cards
Pete Alexander--1918-1926 Rookie Card 1911 M101-2 Sporting News
Cap Anson--1876-1897 Rookie Card 1887-90 N172 Old Judge
Ernie Banks--1953-1971 Rookie Card 1954 Topps
Lou Brock 1961-1964--Rookie Card 1962 Topps
Mordecai Brown 1904-1912, 1916--Rookie Card 1904 W600 Sporting Life
Frank Chance 1898-1912--Rookie Card 1899-00 M101-1 Sporting News
John Clarkson 1884-1887--Rookie Card 1887-90 N172 Old Judge
Kiki Cuyler 1928-1935--Rookie Card 1924 M114 Baseball Magazine
Hugh Duffy 1888-1889--Rookie Card 1887-90 N172 Old Judge
Johnny Evers 1902-1913--Rookie Card 1903 W600 Sporting Life
Clark Griffith 1893-1900--Rookie Card 1887-90 N172 Old Judge
Gabby Hartnett 1922-1940--Rookie Card 1922 W573
Billy Herman 1931-1941--Rookie Card 1932 Chicago Team Issue
Fergie Jenkins 1966-1973, 1982-1983--Rookie Card 1966 Topps
King Kelly 1880-1886--Rookie Card 1879-80 N.Y. Clipper Woodcuts
Ryne Sandberg 1982-1997--Rookie Card 1980 TCMA Reading
Joe Tinker 1902-1912, 1916--Rookie Card 1903 W600 Sporting Life
Billy Williams 1959-1974--Rookie Card 1961 Topps #141
Hack Wilson 1926-1931--Rookie Card 1925 W504 Universal Toy