Don't know if anyone else has access to this information, but in my fledgling career in postal history (Canada and USA) I've been tracking down postal rates so I can decipher my old covers. Just came upon this chart which I think will be really handy. So I thought I'd share.
Thanks Steve. Any link is always helpful. I've printed out the pages I linked above and have them in a binder on the bookshelf next to me. Sometimes it's easier for me to find things on my self, than on the inter-web.