If you have ever noticed how easy it is to navigate Phoenix, you can thank a city design that dates back long before modern development. The Valley’s famously clean street grid has roots in ancient irrigation systems built by the Hohokam more than a thousand years ago.

The Hohokam constructed hundreds of miles of canals to carry water from the Salt River across the desert, creating one of the most sophisticated irrigation systems in North America at the time. When American settlers arrived in the late 1800s, they reused many of these same canal corridors to establish farms and communities. As Phoenix grew, roads were often built alongside these canals or along the same surveyed lines.

That practical approach eventually evolved into the orderly mile by mile grid we know today, where major roads typically run north south or east west and are spaced about a mile apart. Many of the canals themselves still operate today as part of the modern water system run by the Salt River Project.

So the next time you are cruising along a straight Phoenix roadway, there is a good chance you are following a path shaped by ancient engineering, early farmers, and more than a century of city planning.