Thanks in part to a resolution passed by the PTA in 2010, 44 states and the District of Columbia have adopted the Compact.

WHITEHOUSE: Dr. Jill Biden Talks with the PTA's Executive Board about Supporting Military Kids in Schools | The White House

The City, London's traditional financial district, is also called the square mile, but it is no longer as compact as it once was.

ECONOMIST: A survey of financial centres: Capitals of capital | The