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The majority of the nation’s priciest zip codes are located — no surprises here — in California.

California’s San Francisco, Los Angeles, San Jose and San Diego have the highest share of zip codes in which zero percent of homes are “reasonably affordable” to the typical buyer, according to new research by real estate site Trulia.

Homes were considered affordable if 30 percent or less of the metro’s median monthly income was needed to afford a mortgage payment and other expenses, such as property taxes.

San Francisco is the most expensive metro in the study. More than 23 percent of zip codes in the area are considered 100-percent unaffordable to the average home buyer. The city has a median home value of $946,700.

On the flip side of the coin, cities in Missouri, Pennsylvania, Ohio and Indiana boast the highest share of affordable zip codes in the country, according to the study.

The most affordable areas included Pittsburgh, Penn., Colombus, Ohio, St. Louis, MO, Kansas City, MO and Indianapolis, Ind.

In Pittsburgh, for example, 22.5 percent of homes are 100-percent affordable to the average home buyer, with the median home value clocking in at $143,200.

Here are the most expensive areas:

  1. San Francisco, Calif.

Share of zip codes where 100% of homes are unaffordable: 23.5%

Median home value: $946,700

2. San Jose, Calif.

Share of zip codes where 100% of homes are unaffordable: 19%

Median home value: $1,193,600

3. Los Angeles, Calif.

Share of zip codes where 100% of homes are unaffordable: 15.9%

Median home value: $649,500

4. New York, NY

Share of zip codes where 100% of homes are unaffordable: 9.3%

Median home value: $442,500

5. San Diego, Calif.

Share of zip codes where 100% of homes are unaffordable: 8%

Median home value: $590,700

These are the most affordable areas:

  1. Pittsburgh, Penn.

Share of zip codes where 100% of homes are affordable: 22.5%

Median home value: $143,200

2. Colombus, Oh.

Share of zip codes where 100% of homes are affordable: 19.1%

Median home value: $192,000

3. St. Louis, MO

Share of zip codes where 100% of homes are affordable: 18.2%

Median home value: $166,500

4. Kansas City, MO

Share of zip codes where 100% of homes are affordable: 16.4%

Median home value: $192,900

5. Indianapolis, Ind.

Share of zip codes where 100% of homes are affordable: 13.9%

Median home value: $166,800