Welcome, the information about serial number 15370 is available at
https://www.wcha.org/forums/index.php?threads/13665/ but it shows a 16 foot long canoe. It appears that you are asking about a 20 foot one. My guess is that you may actually have the Old Town canoe with serial number 115870. This is an 20 foot long, AA (or top) grade, guide model with Western red cedar planking, open mahogany gunwales, mahogany decks, mahogany thwarts, mahogany seats, half ribs, and a keel. It was built between May and March, 1938. The original exterior paint color was dark green. It shipped on March 14th, 1938 to Johnstown, Pennsylvania. A scan of this build record can be found below.
This scan and several hundred thousand more 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/catalogs/old-town/records/ if you want more details. I hope that you will donate, join or renew your membership to the WCHA so that services like this can continue. See
http://www.wcha.org/about-wcha to learn more about the WCHA and
http://www.wcha.org/store/membership to renew.
It is possible that you could have another number or manufacturer if this description doesn't match the canoe. The information at
https://www.wcha.org/forums/index.php?threads/791/ may help if the numbers are hard to read. The Carleton canoe with number 15370 is 17 feet long. Kennebec put this number on a 16 foot long canoe and a 17 foot long boat. There are no 20 foot canoes in the 15370x group and 115370 is a 15 footer. Canoes with a family connection are always extra special,
Benson