5 Most Expensive Zip Codes in the US New York City Tops Forbes' 5 Most Expensive U.S. Zip Codes New York Metro Area and Silicon Valley Dominate Forbes' Priciest Zip Codes A lack of inventory is driving real estate prices higher, especially in the most expensive zip codes in the country. Forbes released on Tuesday its annual list of the zip codes with the priciest housing. While the usual suspects made the top five, a New York City zip code topped the list for the first time since Forbes began collecting this data several years ago. Forbes and Altos Research pulled pricing data for more than 22,000 zip codes in the U.S. from June 28 to Sept. 28, then analyzed the 500 most expensive. Only single-family homes and condominiums were sampled. Multi-family homes and co-ops were left out, which may be one reason New York City, known for its high housing costs, had not reached number one on Forbes' list yet. Four of the most expensive 10 zip codes are in Manhattan. Morgan Brennan, real estate reporter at Forbes, said New York City zip codes surrounding famed Central Park were especially expensive, though the zip code that was most expensive, 10065, had more expensive single-family homes and co-ops. "The regions most popular are these zip codes that hug Central Park, especially with high-end buyers," she said. Wealthy, foreign investors consider it a safe-haven investment. Close behind coming in second is the exclusive, posh Alpine, a suburb in New Jersey, that is usually in the top three each year. Brennan said what is driving the high prices there is a lack of multi-family housing and many multi-million dollar single-family estates. In its analysis, Forbes takes into account not just housing prices, but the amount of time properties are on the market and inventory. Inventory is down about 30 percent on average among all the zip codes that made Forbes' list. This is true especially in Silicon Valley, which is represented on the list by Atherton and Hillsborough, third and fifth, respectively. Because of the tech boom in Silicon Valley, Brennan said inventory is down even more drastically there. Here is the list of the top five most expensive zip codes compiled by Forbes: New York, N.Y. Median home price: $6,534,430 Average days on market: 449 Number of homes on the market: 80 Alpine, N.J. Median home price: $5,745,038 Average days on market: 207 Number of homes on the market: 35 Atherton, Calif. Median home price: $4,897,864 Average days on market: 103 Number of homes on the market: 41 Sagaponack, N.Y. Median home price: $4,180,385 Average days on market: 333 Number of homes on the market: 84 Hillsborough, Calif. Median home price: $4,127,250 Average days on market: 172 Number of homes on the market: 124