In a much debated report released by the Census Bureau last year that showed the resurgence of America's downtowns over the prior decade, a rather crude definition of "downtown" was used: "everything within a 2-mile radius of the local city hall".
As Emily Badger notes, this lack of precision "complicates the efforts of business improvement districts and city officials to back up what's supposed to be one of the great urban success stories of the 21st century (and a big topic at The Atlantic's CityLab summit on urban innovation in New York this week): the migration of employers and residents back downtown, redefining these places from dead zones where you one wouldn't want to be caught at night to full-service, 24-hour neighborhoods."
"With this perennial problem in mind, the Center City Philadelphia business improvement district is releasing a report [PDF] today prepared for the International Downtown Association that tries to offer a new way of counting jobs downtown, measuring where the people who hold them live, and enabling comparisons across cities."
"Surely some people will come up finer revisions of this definition..." adds Badger. "But, for now, the technique is an improvement from measuring how crows fly from City Hall."