The Pocket Watch Database has compiled data covering the major American pocket watch manufacturers and created an easy way to find information using the serial number on the watch movement. Here are a few tips to find information about your pocket watch:
The Waltham Factory Ledgers were compiled around 1900 using existing factory records. Book 1 (this resource) contains information about watches manufacturered by the American Waltham Watch Co. up to serial number 1,500,000. Each ledger entry details the date range, grade, size, and other important data.