Each black dot represents the geometric center of a ZIP code.
Credit Matt Stiles / U.S. Census Bureau
Today marks the 50th anniversary of the Zone Improvement Plan, the network of ZIP codes we use for everything from mail delivery to credit card security.
The U.S. Postal Service began using the five-digit codes on July 1, 1963, hoping they would improve the efficiency and speed of mail sorting. Since then, the codes have assumed a role in the identities of many Americans, helping to define where they live or work.
The National Weather Service predicts triple-digit temperatures in the Southwest until at least Wednesday. The temperature in Death Valley hit 128 degrees Sunday, a record high for June in the United States.
The record-breaking heat that has broiled the Southwest since Friday shows no signs of letting up. According to the National Weather Service, "triple-digit temperatures will be common across the Southwest" through at least Wednesday.
The temperature in Death Valley — where the temperature reached 134 degrees in 1913, the hottest temperature ever recorded on Earth — hit 128 degrees Sunday. That mark set a record high for the month of June in the U.S. The weather service says to expect similar heat today.
Excessive heat warnings will continue for much of the Desert Southwest through Monday. Here, Maria Wieser of Italy drinks water while sightseeing in Death Valley National Park on Friday.
Credit Chris Carlson / AP
A heat wave is broiling America's Southwest, where temperatures are expected to soar past 110 degrees in coming days. Before noon on Friday, temperatures in many parts of southeastern California, Nevada and Arizona had already topped 100 degrees.
An "excessive heat warning" was issued Friday by the National Weather Service, which blames the dangerously high temperatures on "a massive area of high pressure across the Western United States through Monday."
A chart shows estimated tax revenue losses due to online sales in 11 U.S. cities. Figures for 2013 are projections.
Credit IHS Global Insight
Online retail sales are cutting into tax revenue in counties and cities, according to a report issued by the U.S. Conference of Mayors on Friday. They estimate the lost revenue for America's largest cities and counties came to about $2.8 billion for 2011 and 2012, combined.