It is a bookmark from the Milton Public Library of Milton Massachusetts. It dates from April of 1976 and was presented to the library by Milton Savings Bank.
According to the National Information Center Milton Savings Bank had just moved to the address listed in the Bookmark. 40 Adams Street, Milton Village, and so they probably saw this method of advertising as a way to get the word out to the community.
So I wonder if anyone still holds an account with this bank from way back in 1976.
Bookmarks can be fascinating
Milton Public Library: Website, Twitter, Facebook