Although we originally developed the Economic Performance Index to measure national economies, it makes sense to examine US states individually. After all, many states have populations as large as small countries, and most have a gross state product (GSP) and population that rival the GDPs of developed economies.

For example, Alabama has roughly the same number of people as Ireland. Kentucky’s population is almost equal to New Zealand’s. Illinois and Rwanda, too, are about the same size, population-wise. When we consider economic size, California’s economy is about the same size as France’s or India’s. The GSP of Texas competes with the entire country of Canada, while Virginia is on par with Poland.
Besides sheer size, it also makes sense to look at US states individually because of their relative autonomy. Although the primary driver of state economic performance is driven by the national economy, states have a comparatively large degree of autonomy in managing their own economic and fiscal policies. Moreover, they are diverse geographically, culturally, economically, and density-wise. Those factors make a decided difference in how the economy of each has fared over the past few decades.
When we created a state-appropriate EPI, instead of using national inflation figures we created an average regional inflation (ex. the Northeast vs. West Coast) to reflect local conditions. Budget deficit/surplus was reconstructed by splitting expenditure and revenues between federal, state, and local levels. The other two state-specific factors—unemployment and GSP—were all available in public sources.
Here is the 2015 map of US that shows EPI performance for individual states—darker color shows better economic performance:

The overall trend shows that the EPI score improved over time, mainly driven by structurally low inflation and unemployment, while growth rates slowed down after the Great Recession. Inflation rates dropped largely from its peak in the 1980s with an average of more than 5% down to 3% in the early 2000s and below 2% in 2010-2015. GDP growth rates gradually slowed down over time and moved to a “new normal” or structurally lower levels of growth after the 2009 crisis. State deficits have usually reflected the federal-level government policies and have remained elevated after the crisis.
As you can see, the East Coast did particularly well during the 1980s, as well as California and some other West Coast states. In the 1980s, the East Coast states outperformed in their EPI scores mainly due to higher GSP growth rates. Also, higher levels of urbanization on the East Coast kept unemployment levels lower than in the rest of the US.
Twenty years later, however, the picture had radically changed. Going into the Great Recession, the Eastern seaboard and California were doing poorly, while the Midwest and the Northwest did spectacularly well. One main driver was oil. As prices went up, oil-producing states had larger state surpluses and lower unemployment rates, while net energy importers like California suffered higher fuel costs.
As oil prices continued to increase, oil-producing states continued to grow. The Texas economy moved from 30th in the 1980s to 6th during 2010-2015 in the EPI ranking; Louisiana, from a depressingly low 49th place to the 25th; Oklahoma, from 33rd to being in the top seven.
North Dakota moved from 29th position before the crisis (average for 2000-2007) to the first position in 2010-2015, supported by high oil prices during that time, while other states were in stagnation. Mid-western and western states went through the crisis better, with Nebraska moving from 21st to 2nd place, Wyoming from 23rd to 4th. At the same time, California and Florida’s economic performance deteriorated from 19th position to 37th and from 8th to 29th respectively.
While North and South Dakota don’t usually make international news for their economic performance, the two states have consistently had two of the best-performing economies over the last thirty years, even when oil prices were quite low. Besides a high level of GSP growth (North Dakota reached 20% growth in 2012), they have experienced quite low unemployment rates over these three periods.
On the flip side, the ten worst-performing economies in 2010-2015 are something of a mirror image of the 1980s.
Nevada, Massachusetts, New Jersey, Rhode Island, Georgia, and South Carolina were some of the top-performers in the 80s. Thirty years later, they’re at the bottom of our EPI ranking, plagued by high unemployment and low growth rates.
However, we can expect the story to change over the next decade as oil prices continue to drop, resulting in lower energy costs. This will provide a boost to energy-consuming states like California, Virginia, and Massachusetts, as well as to the national economy as a whole.

Read more about EPI and US states.