Trails around portages in North America usually began as animal tracks and were improved by tramping or blazing. In a few places iron-plated wooden rails were laid to take a handcart. Heavily used routes sometimes evolved into roads when sledges, rollers or oxen were used, as at Methye Portage. Sometimes railways were built (Champlain and St. Lawrence Railroad). The basic purpose of most canals is to avoid portages.