The United States is the most secure country in human history. In this world-at-night picture, it is easy to appreciate America’s isolation. Aside from a few dots on the northern edges of the light fields, Canada has no presence. The populated portions of Canada are in essence an extension of the American system. To the south, there is roughly a thousand miles of empty terrain between the American cities of Corpus Christi and San Antonio, and the Mexican core regions. East and west, the Americans are protected by lengthy ocean crossings.
To learn more of how geography shapes national power, see Chapters 2, 3 and 4 of The Accidental Superpower.