NBC News has analyzed economic data from the Federal Reserve and housing market data from Redfin, a Seattle-based real estate brokerage company, to create an interactive map that shows where in the United States people can buy an affordable median-priced home. A home is affordable when monthly mortgage payments do not exceed 30 percent of a household’s monthly income, and the map allows users to adjust their annual household income to see all the local counties, marked by the yellow color, where they can purchase a house that satisfies the income criteria.