Purpose

The purpose of this project is to map an interactive plot of historical phone area codes, as originally specified by Bell System in 1947. We would like to show the area code assigned to U.S. major cities in 1947, their population size according to the 1950 census, and the number of "clicks" it would take to dial that area code on a rotary phone -- major cities tended to be given area codes with a lower number of clicks, to improve efficiency of dialing. On rotary phones, dialing a "1" corresponded to one click, dialing a "9" was nine clicks, and dialing a "0" took the most clicks of all, ten. Populous states with more than one area code were therefore assigned an area code with a "1" in the second digit to reduce the overall time spent dialing. States with only one area code were assigned an area code with a "0" in the second digit.

Tips for user interaction

To see more information, mouse over cities. Select area codes of interest using the chart on the bottom left. As area codes are selected, the scatterplot changes to reflect those selections. To select multiple area codes, use Shift-Click. Double-click to unselect.