Income inequality is becoming the most important economic topic going into this election cycle. The absolute extremes of wealth and poverty are often found in the same area. The annual median household income in the wealthiest towns in America can be as high as three or four times the national median income, and as much as five or six times the income in nearby impoverished communities.

This type of inequality does not occur overnight. To highlight some of the factors that create hyper-wealthy townships, 24/7 Wall St. reviewed income data from some of the wealthiest towns, cities, and boroughs around the country. These places are havens for the nation’s elite, where median home values can exceed $1 million and large proportions of the households earn at least $200,000 annually. These are the richest towns in the country.

Click here to see the richest towns in America.

The richest communities in the country are all quiet suburbs located within commuting distance of a major city, which also offer the most high-paying job opportunities. Four of the 10 wealthiest towns are within commuting distance of New York City, two are close to Dallas, and two are outside of San Francisco.

Being near a major metropolitan area does not guarantee an affluent community. Some of these wealthy towns are just a short drive away from the poorest areas in the country. West University Place, Texas is a suburb of Houston and had an annual median household income of $205,135 and a poverty rate of just 2.3%. South Houston, meanwhile, had a median income of $35,478 and a poverty rate of 32.0%.

One common trend among places with higher income is a greater incidence of households with two earners, and particularly married households with children. There are likely two reasons for this. First, a high rate of two earners per household raises the median household income. Second, people are more likely to raise children in communities they consider to be prosperous, safe, and offering quality education. Of course, only families with a certain level of income have the luxury of these options.

In eight of the 10 wealthiest towns and cities, at least 70% of households consisted of a married couple. At least 30% of married couples in all of these areas had children as well. Nationally, just 48.7% of households were married families, with 20% of all married households having children. In Scarsdale, New York, the wealthiest city, 82.7% of households consisted of a married couple, and nearly half of those had children.

Residents in the wealthiest places in the country are frequently employed in highly-skilled positions in high-paying industries, which require high levels of education. They work in finance positions in New York City or Chicago, or in scientific or other professional careers in the San Francisco Bay Area. The education levels in these communities are especially high. While 86% of adults nationally had at least a high school diploma, at least 97% of adults in the wealthiest city did. Moreover, while 28.8% of adults nationally had at least a bachelor’s degree, more than 70% of adults in nine of the 10 wealthiest cities did. In Winnetka, Illinois, the second wealthiest community, 88% of adults had at least a bachelor’s degree.

To determine the richest towns in the country, 24/7 Wall St. considered median household incomes from the U.S. Census Bureau’s 2013 American Community Survey (ACS). Because many towns in the country are small, data can be unreliable. For this reason, all data used are five-year estimates for the period 2009-2013. Still, data can be subject to sampling issues. We did not consider towns where the margin of error at 90% confidence was greater than 10% of the point estimate of both median household income and population. Also from the ACS, we reviewed poverty rates, median home values, educational attainment rates, the shares of households making less than $10,000 and more than $200,000, as well as the percentage of households that are married, and have children. Industry composition of these towns is also from the ACS.

These are the richest cities in America.