A treasure trove for baseball historians is now available online at the Library of Congress:
Spalding Base Ball Guides, 1889-1939 comprises a historic selection of Spalding's Official Base Ball Guide and the Official Indoor Base Ball Guide. The collection reproduces 35 of the guides, which were published by the Spalding Athletic Company in the late nineteenth and early twentieth centuries. Spalding's Official Base Ball Guide was perhaps the premier publication of its day for the game of baseball. It featured editorials from baseball writers on the state of the game, statistics, photographs, and analysis of the previous season for all the Major League teams and for many of the so-called minor leagues across the nation. The 15 Spalding's Official Base Ball Guides included in this online collection were published between 1889 and 1939.
Each guide contains roughly 350 pages. Happy hunting!
(Hat tip: Baseball Think Factory)