The Chicago, Milwaukee, St. Paul and Pacific Railroad Company Historic District consists of the historic right-of-way of the Chicago, Milwaukee, St. Paul and Pacific Railroad in the Bitterroot Mountains from East Portal, Montana, to the mouth of Loop Creek, Idaho, a distance of 14.5 miles. The district was once part of the railroad's mainline from Chicago, Illinois t…The Chicago, Milwaukee, St. Paul and Pacific Railroad Company Historic District consists of the historic right-of-way of the Chicago, Milwaukee, St. Paul and Pacific Railroad in the Bitterroot Mountains from East Portal, Montana, to the mouth of Loop Creek, Idaho, a distance of 14.5 miles. The district was once part of the railroad's mainline from Chicago, Illinois to Tacoma, Washington.