The point is a general one. Getting a higher salary in California or New York, and then needing to pay more for housing and perhaps other costs of living as well, can easily eat up that higher salary. In fact, the Bureau of Economic Analysis now calculates Regional Price Parities, which adjust for higher or lower levels of housing, goods, and services across areas. Comparisons are available at the state level, the metropolitan-area level, and for non-metro areas within states. To illustrate, here are a couple of maps taken from "Living Standards in St. Louis and theEighth Federal Reserve District: Let’s Get Real," an article by Cletus C. Coughlin, Charles S. Gascon, and Kevin L. Kliesen in the Review of the Federal Reserve Bank of St. Louis (Fourth Quarter 2017, pp. 377-94).
Here are the US states color-coded according to per capita GDP. For example, you can see that California and New York are in the highest category. My suspicion is that states like Wyoming, Alaska, and North Dakota are in the top category because of their energy production.
And now here are the US states color-coded according to per capita GDP with an adjustment for Regional Price Parities: that is, it's a measure of income adjusted for what it actually costs to buy housing and other goods. With that change, California, New York, and Maryland are no longer in the top category. Hoever, a number of midwestern states like Kansas, Nebraska, South Dakota, and my own Minnesota move into the top category. A number of states in the mountain west and south that were in the lowest-income category when just looking at per capita GDP move up a category or two when the Regional Price Parities are taken into account.
When thinking about political and economic differences across states, these differences in income levels, housing prices, and other costs-of-living are something to take into account.