The State Similarity Index attempts to quantify how similar states are to each other relative to other states. The index is a statistically-based way to measure this. 20% of the index is based on geography. 10% of a state’s geography score (2% of the overall State Similarity Index score) is based on a state’s topography. The following factors were included in the calculation:
Surface Freshwater
Michigan is highest percentage of freshwater, since it borders four of the five Great Lakes. No other state borders more than two. The state also has many smaller lakes that dot its landscape. In contrast, New Mexico has the lowest percentage of surface water in the country. Not only is it one of the driest states, but also it does not have any large reservoirs of water created by dams like in Nevada or Arizona.
Source: US Census
States were grouped by percentage of surface freshwater:
.25-1, 1-1.75, 1.75-2.5, 2. 5-3.75, 3.75-5, 5-7.5, 7.5-10, 10-15, 15-20, 20-30, 30-40
Coast-Land Area Ratio
Measuring the amount of coastline is quite a difficult task. It is dependent on how fine the measurements are made. CRS’s method of calculating coastline, using large scale nautical charts, shows that Hawaii has the largest ratio of coast to land area. Meanwhile, NOAA’s calculation shows that Maryland has the most coastline compared to its land area. The Chesapeake Bay has a very curvy coastline as well as many small islands. NOAA’s calculation also includes coastline along the Great Lakes, not just the oceans. Obviously landlocked states have the lowest ratio, since they have no coastline.
Source: Wikipedia
States were grouped by coastline to land area ratio (average of CRS and NOAA methods):
Landlocked, 0-25, 25-50, 50-100, 100-200, 200-400
Water Surroundedness
Hawaii is the only state that has no land borders, since it is a group of islands in the Pacific Ocean. It should be noted that Rhode Island’s name is misleading, since it originally referred to one of the islands that is part of the larger state. Not only are some states landlocked, but a few are doubly landlocked, including Colorado, Kansas, Nebraska, Utah, and Wyoming. They are all located in either the Great Plains or the Rocky Mountains.
Source: Wikipedia
States were grouped by length of water borders compared to land borders:
Landlocked, 1-25%, 25-50%, 50-75%, 75%-99%, Island
