Buying a home is likely the largest purchase most Americans will ever make. But while in some areas homeowners are more easily able to afford to buy, in others they need to spend much more of their income on their house. A home’s affordability varies considerably depending largely on where the buyer lives, but also on a variety of other factors.

Real estate tracking firm RealtyTrac calculated income-to-price affordability ratios for 2,270 counties across the U.S.. The affordability rate is the percentage of the area’s estimated median household income that is needed to make monthly payments on a median-priced residential property in that area. A higher ratio means the affordability is lower, and vice versa. Based on RealtyTrac’s data, Chattooga County Georgia residents have the most affordable houses in the nation.

The majority of the most affordable markets have become more affordable over the past decade. Current affordability rates in all of the 10 most affordable counties are substantially lower than historical figures. For instance, in Hardee County, Florida, households have had to earn at least 13.1% of the median income in the last 15 years to cover the costs of homeownership, which include mortgage payments, homeowner’s insurance and property taxes. As of May, just 7.2% of Hardee County’s median income was required to cover the same costs.

Click here to see the 10 most affordable housing markets in America

Click here to see the 10 least affordable housing markets in America

In general, residents of these counties are poor. All 10 of the most affordable housing markets are in areas where the typical household earned less than the national median, including four areas in which the median income was less than $40,000. Notably, Lake County, Tennessee and Lamar County, Georgia had among the lowest median annual incomes in the nation between 2008 and 2012.

Of course, one of the major reasons these markets remain so affordable is simply home prices. As last year, the average price of a home in half of the most affordable counties on this list with available data was less than $50,000 — far less than in most markets. Residential properties in Lake County, Tennessee and Edgecombe, North Carolina cost just over $36,000 on average, by far the lowest average price and a considerable decrease from previous years.

Low demand is also a prominent feature of these areas. Michigan, and in some cases the greater rust belt area, typically share in a very low affordability rate. According to Daren Blomquist, vice president of RealtyTrac, not only was “the correction in [Michigan’s] home prices unparalleled,” but also the “struggling population began to move out.”

With the exception of Michigan’s Saginaw and Wayne counties the most affordable residential counties are located in the southern United States. As Blomquist explained, housing markets in parts of the southern United States are likely more affordable due to low demand.

Both geographical and policy limitations can affect a region’s affordability. In a majority of the most affordable housing markets, there are very few geographical limitations. Additionally, in these “areas you just have less constraints on growth and on building so you have an unconstrained supply,” explained Blomquist.

Another way to measure the relationship between low demand and abundant supply — primarily for metropolitan counties — is to use population density metrics. A sparsely populated area will likely have lower demand for residential homes compared to more densely populated areas. Seven of the counties reviewed had less than 100 residents per square mile in 2011, among the more sparsely populated areas reviewed.

To identify America’s most affordable housing markets, 24/7 Wall St. reviewed affordability rates by county calculated by RealtyTrac for May 2014. The affordability rate is the percentage of the county’s estimated median household income needed to make monthly payments — on mortgages, property taxes, and homeowner’s insurance — on a median-priced residential property. RealtyTrac figures also assume that homebuyers take a fixed 30-year mortgage at prevailing rates with a 20% down payment. The property taxes are calculated at 1.4% of the home price. These calculations use a 2014 median income estimate.

RealtyTrac calculated the affordability rate each month from January 2000 to May 2014. We excluded counties where the recorded affordability ratio for May significantly diverged from preceding months. RealtyTrac also provided historical averages, as well as annual peak and trough values of the affordability ratios at the county level. Figures on median household income are five-year estimates from the Census Bureau’s 2012 American Community Survey. Gross Metropolitan Product (GMP) figures are from the Bureau of Economic Analysis and are 2012 estimates.

These are the 10 most affordable housing markets in America.

10. Wayne County, Mich.
> Affordability rate: 7.25%
> Historical avg. affordability: 12.6%
> Household median income: $33,066
> Population density: 2,944.2 per sq. mile

Wayne County has some of the most affordable homes in the nation, although this doesn’t imply economic health. Households in the area earned just $33,066 between 2008 and 2012. Despite having some of the lowest income, households were able to easily afford area homes because housing prices were also exceptionally low. Wayne County is home to Detroit, which filed for bankruptcy in July 2013. Home prices in the area have been on a downward trajectory for decades and suffered a severe blow during the recession. Similarly, the county’s population has dwindled during that time from 1.82 million in 2010 to 1.76 million last year. Wayne area homes were most affordable in 2009, when just 3.4% of a typical income was needed to afford a median-priced home.

9. Hardee County, Fla.
> Affordability rate: 7.24%
> Historical avg. affordability: 13.1%
> Household median income: $40,316
> Population density: 43.7 per sq. mile

Homes in Hardee County are among the nation’s most affordable. The county’s affordability rate of 7.24% is well below the 14-year affordability rate average of more than 13%. Residential properties were the least affordable in 2006, when nearly a third of the area’s median income was required to make payments on a typical home. Now, Hardee homes are near their previously most affordable levels in September 2011. At that time, Hardee residents needed 7.18% of the area’s median household income for payments on a median-priced home.

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8. Saginaw County, Mich.
> Affordability rate: 7.10%
> Historical avg. affordability: 12.0%
> Household median income: $42,488
> Population density: 248.8 per sq. mile

Saginaw County, with nearly 200,000 residents, is among the largest of the nation’s most affordable counties for home buyers. When it was least affordable, a home in Saginaw County required residents to earn slightly less than 20% of the median household income. As of last year, the average price paid for a home was just $63,294, lower than in most counties. The city of Saginaw, the largest city in the county, has especially struggled from a weak housing market. A declining population and urban blight, caused by residents moving to the suburbs, have long been problems for the city of Saginaw.

7. Lamar County, Ga.
> Affordability rate: 6.92%
> Historical avg. affordability: 11.4%
> Household median income: $33,661
> Population density: 99.1 per sq. mile

Lamar County homes are exceptionally affordable even when compared to other relatively low-income areas. A typical Lamar household earned just $33,661 between 2008 and 2012, considerably lower than the national median household income of $53,046. Over the last 14 years, as homes have become less affordable in the United States, they have become more affordable in Lamar. While residents today need to only earn 7% of a typical income, they historically needed an average of 11.4% to afford a median-priced home. Affordable housing in Lamar may be connected to a recent housing boom in the greater Atlanta metro area, where construction projects and home purchases have risen dramatically in recent years. While increasing demand nearby may lead to higher demand for homes in the county, the increases in supply may be keeping prices low for the time being.

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6. Obion County, Tenn.
> Affordability rate: 6.88%
> Historical avg. affordability: 9.7%
> Household median income: $45,919
> Population density: 58.4 per sq. mile

While average home prices in Obion County have been quite low, they have also remained relatively flat since 2012, at just around $50,000. Between 2008 and 2012, a typical Obion household earned $45,919 annually, considerably less than the national median of $53,046. Since January 2012, the affordability rate has changed very little as well, rising less than one percentage point. Additionally, homes in Obion are more affordable today compared to the area’s historical affordability rate. Since January 2000, only 9.74% of income was needed to make payments on a median-priced home, on average. Even at their least affordable, Obion homes were among the most affordable reviewed.

5. Barnwell County, S.C.
> Affordability rate: 6.81%
> Historical avg. affordability: 7.9%
> Household median income: $35,219
> Population density: 40.8 per sq. mile

Barnwell residents needed 6.8% of the area’s household median income to afford a median-priced home, nearly double the rate in January 2013, when homes were most affordable. While the area’s housing market has become less affordable, prices have fallen each year since 2010, when an average home cost $58,666. The average home price was just $36,918 last year, among the lowest home prices in the country. A typical household earned $35,219 annually between 2008 and 2012, also among the lowest nationwide.

4. Upson County, Ga.
> Affordability rate: 6.31%
> Historical avg. affordability: 10.6%
> Household median income: $37,601
> Population density: 83.4 per sq. mile

Like many of the counties with the most affordable housing, Upson residents are quite poor. The typical household earned only $37,601 between 2008 and 2012, and over 9.4% of the population was unemployed. By contrast, the national median household income was $53,046 annually over that period. The historical affordability rate is 10.65%. Yet, the proportion of income needed to afford a home in Upson County has steadily decreased since March 2007, from more than 16% to 6.31% as of May 2014. Currently, the affordability rate is slightly above the historically lowest level the historically lowest level of 5.42% set in October 2011.

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3. Edgecombe County, N.C.
> Affordability rate: 6.17%
> Historical avg. affordability: 7.2%
> Household median income: $40,726
> Population density: 110.9 per sq. mile

Affordable housing in Edgecombe County is among the most readily available in the nation. While the region’s unemployment rate was relatively high at 11.1% this May, residents are not burdened with excessively high homeownership costs. With a median household income of more than $40,000 between 2008 and 2012 and an average home price of just $36,042 last year, annual incomes often exceed area home prices. Both were among the lower figures in the nation. While affordability does not always indicate a healthy housing market, foreclosures in Edgecombe fell more than 42% between the first quarters of 2013 and this year.

2. Lake County, Tenn.
> Affordability rate: 5.75%
> Historical avg. affordability: 7.1%
> Household median income: $33,512
> Population density: 46.9 per sq. mile

While Lake County’s nearly 8,000 residents are relatively poor, Lake County homes are extremely cheap. A typical household earned roughly $33,500 annually between 2008 and 2012, nearly the lowest household median income. Last year, homes cost around $36,500 on average, an increase from previous years, but still among the lowest figures for any county. Area homes reached the most affordable level in February of this year, when just 3.17% of the county’s median income was necessary to afford typical housing.

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1. Chattooga County, Ga.
> Affordability rate: 3.75%
> Historical avg. affordability: 7.2%
> Household median income: $41,864
> Population density: 82.1 per sq. mile

Among all American counties, Chattooga residents needed the smallest percentage of their annual incomes to afford their homes. RealtyTrac estimates that Chattooga households spent only 3.75% of their income on monthly home-related payments, below the historical average of more than 7.2%, and lower than in any month since RealtyTrac started collecting data. This is also despite a considerable jump in home prices, from an average of $39,560 in 2012 to an average of $49,196 last year.

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