Roadmap needs this file in the roadmaps folder, not in a sub-folder, for it to access the files.
$ cd /media/mmc2/roadmaps wget -O http://roadmap.digitalomaha.net/maps/rnfMB.tar.gz | tar -xzf -
$ ls MB MN ND SB usdir.rdm
$ grep -i Fargo usdir.rdm Fargo-Odell Fargo West Fargo $ grep -i -B1 Manitoba usdir.rdm MB Manitoba $ grep -i peg usdir.rdm Pegram $ grep -i peg MB/usc89001.rdm Peguis Winnipeg