There are many different definitions of exactly where the Arctic ends and more temperate regions begin. Both in terms of human settlement and from a geographic standpoint, the Arctic is probably best defined as the area north of the treeline. Simply put, the treeline is the border between southern boreal forests and northern tundra and it corresponds with a climate zone where the cold Arctic air meets warmer air masses from farther south. Here the average daily summer temperature does not rise above 50° F. It is a transition zone where continuous forest gives way to the sporadic low lying trees of the taiga and finally to treeless tundra. In North America, this boundary is a narrow band, but in Eurasia it can be up to 200 miles wide.

Another popularly defended delimiter is the Arctic Circle (latitude 66.5° North). North of this latitude, periods of continuous daylight or night last up to six months at the North Pole. Because the Earth spins around the Sun on a tilted axis, this imaginary line denotes the southernmost limit of the midnight Sun, or 24-hour summer day. However, this definition includes the relatively mild and forested lands of Norway, while excluding the decidedly "arctic-like" regions of southern Greenland and Canada's Hudson Bay.

A third definition places the edge of the Arctic region along the 50° F isotherm (a line connecting points of equal temperature), the line north of which the average temperature does not rise above 50° F in any month of the year. This definition does not include many areas of Russia, Alaska, Canada, or Scandinavia that lie well above the Arctic Circle.

Yet another definition would only recognize Arctic cultural areas -- those areas with indigenous Arctic peoples and including their traditional polar hunting grounds.

For this web site, we will try to encompass all of these definitions to provide the most comprehensive and all-inclusive coverage of the region as possible.