Mortgage rates may be a function of free markets, but real estate taxes are a function of government. And, depending on where you live, your annual real estate tax bill could be high, low, or practically non-existent.

Compiling data from the 2009 American Community Survey, the Tax Foundation, a non-partisan educational organization in Washington D.C., published property taxes paid by owner-occupied households, county-by-county.

The report shows huge disparity in annual property taxes by region, and by state.

As a percentage of home valuation, Southeast homeowners tend to pay the fewest property taxes overall, while Northeast homeowners tend to pay the most. But statistics like that aren’t especially helpful. What’s more useful is to know how local real estate taxes stack up as compared to local, median household incomes.

Not surprisingly, real estate taxes are least affordable to homeowners in the New York Metro area. The 10 U.S. counties with the highest tax-to-income ratios physically surround New York City’s 5 boroughs. The areas with the lowest tax-to-income, by contrast, are predominantly in southern Louisiana.

A sampling from the Tax Foundation list, here is how select counties rank in terms of taxes as a percentage of median income:

• #1 : Passaic County (NJ) : 9.7% of median income
• #6 : Nassau County (NY) : 8.6% of median income
• #15 : Lake County (IL) : 7.2% of median income
• #18 : Cheshire County (NH) : 7.1% of median income
• #70 : Travis County (TX) : 5.0% of median income
• #90 : Marin County (CA) : 4.6% of median income
• #110 : Middlesex County (MA) : 4.4% of median income
• #181 : Sarasota County (FL) : 3.9% of median income
• #481 : Douglas County (CO) : 2.4% of median income
• #716 : Maui County (HI) : 1.3% of median income

The U.S. national average is 3.0 percent.

The complete, sortable list of U.S. counties is available at the Tax Foundation website. For specific tax information in your neighborhood or block, talk with a real estate agent.

As part of the Census Bureau’s data collection activities from 2005-2009, a number of interesting charts have been published at http://census.gov.

The data should not be confused with Census 2010 — a separate survey conducted every 10 years. This is the first-ever, 5-year American Community Survey. Based on data from 3 million households, it details social, economic, housing, and demographic data “for every community in the nation“.

Among the surveys:

• Median Household Income, Inflation-Adjusted To 2009 Dollars (Chart)
• Median Housing Value Of Owner-Occupied Housing Units (Chart)
• Percent Of Households That Are Married, With Children Under 18 (Chart)

The ACS survey also charts average commute time by county. The chart is shown at top.

Whether you live in a “long commute” town like Richmond, NY (40 minutes), or a “short commute” town like King, TX (3.4 minutes), rising gas prices have made commute times and distances relevant to everyone.

Since the start of 2011, the average price for gasoline is higher by 54 cents per gallon. Assuming 22 miles per gallon on a passenger car, that’s an increase of 2.5 cents of gasoline per mile driven in the last 90 days. It’s a cost that adds up quickly, and can affect a household budget. Plan for higher pump prices moving forward, too. Historically, gas prices surge between April and June.

The American Community Survey is loaded with charts and data. It can tell you a lot about your current neighborhood, and any neighborhood to which you may want to relocate. Then, to bridge the ACS data with community details such as school performance and typical home prices, talk to a real estate professional.

The value of a home is based on the basic economic principle of Supply and Demand. When the number of buyers exceeds the number of sellers, home prices rise. Conversely, when sellers outnumber buyers, home prices fall.

There’s always a opening price point for negotiation and that figure often factors in specifics like square footage, number of rooms, and finishes and amenities. Location matters, too.

On a ZIP code-by-ZIP code basis, prices can vary wildly and it’s tiny, tony 91008 — located in Duarte, California — that tops the 2010 Forbes list of America’s Most Expensive ZIP Codes. Home to fewer than 1,400 residents of Los Angeles County, the ZIP code’s median home cost is $4,276,462.

By contrast, the median home cost across all of Duarte’s ZIP codes is just $358,454.

As listed by Forbes, America’s 10 most expensive ZIP codes are:

1. Duarte, CA (91008) : $4,276,462
2. Atherton, CA (94027) : $4,010,200
3. Rolling Hills, CA (92074) : $3,892,456
4. Alpine, NJ (07620) : $3,814,885
5. New York, NY (10014) : $3,785,445
6. Beverly Hills, CA (90210) : $3,684,150
7. New York, NY (10065) : $3,626,001
8. Belvedere (94920) : $3,283,269
9. New York, NY (10012) : $3,221,371
10. Santa Barbara (93108) : $3,151,220

The real estate market is a local one, as evidenced by the Forbes list. Even within large cities like New York, there are areas that stand out from the pack in terms of cost and affordability and the same is true for all cities.

Therefore, when you need local market data for rosslyn , look past the “national statistics”.  Talk to a real estate agent with local market knowledge instead. It’s the most reliable way to get data that matters.