To determine the most expensive ZIP codes in every state, 24/7 Wall St. reviewed data provided by Attom Data Solutions, a real estate and property data provider. ZIP codes are ranked based on median sales price of condos and single-family homes in 2020. Only ZIP codes with at least 1,000 single family homes and condos and with at least 100 sales in that time frame were considered. The estimated market value is determined by Attom’s automated valuation model. Data on median household income and the share of households earning $200,000 or more annually are five-year estimates at the ZIP code level for 2015-2019 from the U.S. Census Bureau’s American Community Survey. Five states without ZIP code-level price data — Maine, Massachusetts, New Hampshire, South Dakota, and Vermont — were excluded from analysis.