With the 2016 Iowa caucuses next Monday about to kick off the election process for the next President of the United States, questions about the economy are at center stage. In particular, income distribution has become a major discussion subject among presidential hopefuls. Indeed, household income varies dramatically across the country, not only from state to state, but also across counties within states, and these regional differences may affect the results at the polls.

With the exceptions of Arizona, Delaware, Hawaii, and Vermont, median household income in each state’s wealthiest county exceeds the corresponding statewide figure by more than $10,000. Based on data from the Census Bureau’s American Community Survey, 24/7 Wall St. reviewed the richest county in each state.

Some states have greater income inequality than others. In all but 10 states, the typical household income in the poorest county is at least $30,000 less than that of the richest county. In some of these states, the income gap is far greater. A typical household in Loudoun County, Virginia’ wealthiest, earns $96,220 — more than three times the typical household in Martinsville City, the state’s poorest. This is the widest such income gap in the nation. In Delaware, on the other hand, the income gap between the richest and poorest counties is only $11,352, the smallest gap.

Click here to see the richest county in each state.

Click here to see the poorest county in each state.

The richest counties tend to be suburbs of the nation’s largest cities. Nassau County, the wealthiest area in New York, is within commuting distance of Manhattan. Suburbs of Washington D.C., Philadelphia, Chicago, San Jose, and Raleigh are also among the wealthiest counties nationwide.

Households in each state’s richest county tend to be wealthier than households nationwide, without exception. However, while a county may be the wealthiest in a particular state, it may not be especially wealthy compared to the rest of the nation. In Benton County, Arkansas, for instance, the typical household earns $56,325 a year, only slightly more than the $53,482 the typical American household earns.

In five states, the wealthiest county boasts a six figure median household income. And in two states, Maryland and Virginia, median household income in the wealthiest county is more than double the national median household income. In Howard County, Maryland, a typical household earns $110,133, and in Loudoun County, Virginia, median income is $123,966 a year.

The average resident of a state’s wealthiest county tends be better educated than the average American. In only six states, the collegiate attainment rate — the percentage of adults with at least a bachelor’s degree — in the wealthiest county is lower than the national rate. Only three states have a higher collegiate attainment rate than that of their wealthiest county. Higher educational attainment can qualify individuals for higher-paying jobs and increase median household income overall.

Similarly, a healthy economy often coincides with higher incomes. With just three exceptions, all of the wealthiest counties have unemployment rates lower than the national rate.

To identify the wealthiest county in each state, 24/7 Wall St. reviewed five-year estimated median annual household incomes from 2010 through 2014 from the U.S. Census Bureau’s American Community Survey (ACS). In order to be considered, counties or county-equivalents had to have a population of at least 10,000 people. Five-year estimated educational attainment and poverty rates also came from the ACS. Annual unemployment rates are for 2014 and came from the Bureau of Labor Statistics.

These are the richest cities in each state.