The brand originated with the Bloch Brothers of Wheeling, PA, who started out making cigars in 1879. They made the chewing tobacco from cigar wrapper clippings. That sounds pretty unappealing to me, but I guess it worked because at one point they had more than 20,000 advertisements on barns across the country. Apparently some people like to go searching for the barn signs and you can buy various Mail Pouch memorabilia on ebay.
The sign's on 5th St. NE between Hennepin & 1st.