The land border between Canada and the United States, stretching 8,891 kilometers, is often called the longest undefended border in the world. However, since 11 September the border has become harder to cross. At a time when Europe was tearing down borders (a process that may be somewhat regretted now), the United States and Canada were building one up. This site seeks to understand the history of the border between the two countries, changes to the defense of the border, and pecularities arising from this process. Furthermore, it is the hope that better understanding how and why border security has increased will point to ways that the border can be opened up to allow for a freer flow of goods, peoples, and ideas.