ATLANTA – Interstate 75 is a north-south route, while Interstate 20 is runs east-west. Most people know that’s the case because they’re either familiar with the roads or they know that highways with odd number designations run north-south while even number roads run east-west.
What you may not have known is that this wasn’t always the case. It wasn’t until the 1920s – once the automobile revolution was in full swing – that officials decided to start using standard signs and the odd-even road designations for the nation’s 3 million miles of roads.
Today, there are 4 million miles of roads, including 47,000 miles of interstate highways, according to the U.S. Census Bureau. And because of the decision to move to the odd-even highway designations along with standard signs, one made 84 years ago this week, it’s easier to traverse the country and see all that it has to offer.