Company towns used to be a defining feature of the American economy. Nowadays, as Raul at HowMuch.net notes, thanks to globalization and offshoring, it is much harder to find employers that exert such influence over a small town (with a few notable exceptions).

That being said, specific industries still tend to grow in clusters and can dominate the economy of a particular region. To understand this new reality, we mapped the most important industries by state according to the U.S. Bureau of Economic Analysis, which takes into account an industry’s collective output as a percentage of the overall GDP. For simplicity, we excluded government jobs and real estate.

The result is one of the easiest snapshots of the U.S. economy you will ever find.

Source: HowMuch.net

The government groups companies into particular industries using the North American Industry Classification System (NAICS). Basically, someone looks at a company and decides where it belongs on a list of industries. This is more complex than it sounds, especially if a parent company holds many different unrelated subsidiaries (like Amazon), or when a business model strides the line between different industries (anyone care to debate if Airbnb is a technology company or in the hospitality industry?). We simply generated a color-coded map of the results of this debate.

You can immediately see some interesting groupings in the map.

Computer & electronics companies dominate the West Coast, oil & gas remains ascendant in the Southwest, and insurance companies take the greatest market share in the Upper Midwest.

Take a look at the deep South, where you see a lot of red signifying the ambulatory healthcare services industry. This single industry dominates in 13 different states. Think about the Fortune 500 companies headquartered in these places, and it’s pretty easy to understand why these industries are so important. For example, Apple, Facebook, and Google are all headquartered in Silicon Valley in California.

Things tend to be much more diverse across the Northeast, where you see many different industries all grouped together. This is also easy to explain: it’s one of the most population-dense places in the country and it has the smallest states in terms of geography. This environment lets a lot of different industries grow together.

Factory towns may be a thing of the past, but it remains true today that similar businesses tend to grow and expand in areas with the same economic conditions.

This is true for less populous states like North Dakota and places with big cities too, like Colorado. If you’re looking for a job in one of these states, then our list gives you a good idea of where the biggest opportunities might be.