The Old Town canoe with serial number 131987 is a 17 foot long AA grade OTCA model with half ribs, outside stems and a keel. The canoe was built between March and May 1941. The original exterior canvas covering was Design #45, a copy of the design has been attached. The original ship date was June 17, 1941 to Scranton, PA. A scan of this build record can be found by following the link behind the attached thumbnail image below.
This scan and several hundred thousand others were created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others. A description of the project to preserve these records is available at http://www.wcha.org/ot_records/ if you want more details. I hope that you will join or renew your membership to the WCHA so that services like this can continue. See http://www.wcha.org/wcha/ to learn more about the WCHA and http://www.wcha.org/join.php to join.
It is also possible that you could have another number or manufacturer if this description doesn't match your canoe. Feel free to reply here if you have any other questions.