Both Suffolk and Nassau counties recently received the number one spot in FindTheBest's list of "The 15 most expensive places to live in America."

"Nassau and Suffolk Counties, on Long Island, aren't the highest in the country in terms of housing, taxes, or healthcare, but they're up there in each category, and that's enough to make the area the most expensive place to live in America," an article in Business Insider reads. The rankings were determined by a cost of living index created by FindTheBest based on 2013 family budget estimates for housing, taxes, healthcare, childcare, transportation, and other necessities from the Economic Policy Institute to compare, in over 600 counties and metro areas across America, according to the article.

The average overall index for US cities and metro areas is 100. If a city has an index of 120, that means it is 20 percent more expensive than average, and if a city has an index of 80 that means it is 20 percent cheaper than average.

Nassau-Suffolk had a local index of 155 and a State index of 120, according to the list.

The high property taxes and expensive real estate is what makes the counties number one, according to the list. In addition, the fact that the Hamptons is a hot spot in the summer for the rich and famous helps boost Long Island to the top of the list.