America has a lot of water. It may not seem like it, given the wildfires, the droughts, the New Mexican towns running dry. But the United States has more freshwater than all but a small handful of countries (Brazil, Canada, Russia). Each year, there is enough to cover all 50 states in a foot of water.
The rich blue of the image is a bit deceptive. The Mississippi looks no larger than the Rio Grande, lakes and reservoirs are white spots, and even long-dry seasonal creekbeds show up as blue lines. Looking at the close-up of California, you would never guess that the vast majority of surface water is in the North (until it’s funneled south by the California State Water Project), or that by the time the Rio Grande hits Southern Texas, it’s but a shadow of its upstream self.
Still, it’s an awesome sight to behold. And if you’re the web developer type, you will appreciate that Minar has documented his work at length on GitHub, where he includes some suggestions for future projects, like making it more clear how much water is in each river.