The Appalachian region has always had to allocate much resources and time into transportation due to the region's notable and unique geography. Mountainous terrain and commonly occurring adverse weather effects such as heavy fog and snowfall made roads hazardous and taxing on the traveling vehicles. Initially, European settlers found gaps in the mountains, among them the Cumberland Gap and the Wilderness Road. Another notable challenge of Appalachian travel is the political elements of constructing transportation routes. Most travel systems are funded by municipalities, but since The Appalachian area has several different states it can be difficult for the various governments to agree on how to work on transportation. The most influential forms of travel in the Appalachian region are based on water trading routes, roads and railroads.