McDonald’s (NYSE: MCD), with almost 16,000 outlets, is the largest fast-food hamburger chain in the United States. Many of the states where McDonald’s iconic Golden Arches dominate the landscape are also, coincidentally, states with the highest rates of obesity and deaths due to heart disease.

The circumstantial evidence may be there, but no studies demonstrate a direct link between McDonald’s specifically and adverse health outcomes. Academic research does, however, show high concentrations of obesity and other negative health outcomes where there are clusters of fast food restaurants of any type.

24/7 Wall St. reviewed the 10 states with the highest concentration of McDonald’s restaurants, measured as outlets per 100,000 residents from restaurant reviewer and data compiler Menuism. Six of the 10 states also reported the highest obesity rates in the country. At the other end of the scale, four of the 10 states with the lowest concentration of McDonald’s outlets had among the lowest obesity rates.

While there are of course other fast food chains in the country, the association between McDonald’s and many negative health outcomes is often stronger than it is with other chains. Of the 10 states with the greatest concentration of major fast food restaurants, excluding McDonald’s, three have among the lowest obesity rates in the country and none are among the 10 highest.

Click here to see the states with the highest concentrations of McDonald’s restaurants.

Fast food consumption may lead to negative health outcomes. However, the concentration of fast food stores does not account for consumption levels. There are also many other factors, such as low income, high poverty rates, and distance from sources of fresh fruits and vegetables, which contribute to negative health outcomes. The states with the highest obesity rates share a number of these factors. They have some of the lowest household incomes in the country and, correspondingly, some of the highest poverty rates.

Academics who have authored separate studies on fast food restaurants and negative health outcomes differ in their conclusions.

Dr. Lewis Morgenstern, a professor of neurology and director of the stroke program at the University of Michigan Hospital, led a study into the relationship between the concentration of fast food restaurants in a neighborhood and strokes in that neighborhood.

In an interview with 24/7 Wall St. Morgenstern said “we don’t really know, in most of these studies, including the one that I did, that anybody in these neighborhoods who had a stroke ever ate a french fry.” He added, “In the neighborhoods where fast foods are, people tend to have more strokes, but whether it’s some aspect of the neighborhood or the people that live in the neighborhood or the fast food itself, we have no idea.” Obesity, he noted, is a risk factor for strokes.

The author of a separate study had a somewhat alternative view. “Fast food seems to be something that is an indulgence for us,” said Daniel Kruger, professor of health education and health behavior at the University of Michigan School of Public Health. Consuming fast food may be ok in moderation, but eating too much of it can result in a range of adverse health outcomes.

Kruger’s study found a high local concentration of fast food outlets is itself a risk factor. “The main point of our study was that people have a lot more of these fast food restaurants around them, and they’re going to have higher obesity,” he said. Kruger explained how the high frequency of fast food restaurants like McDonald’s is often representative of a poor landscape, in which multiple factors can lead to poor health.

While Kruger cited a study that suggested some fast food outlets serve less nutritious food than others, like Morgenstern, he would not single out McDonald’s or any other chain.

“I don’t think that we can blame the company at this point,” Morgenstern said. “It would be nice if they helped in the research to try to figure out whether the products that they sell are related to negative health, but I don’t think we know that at this point. We need more research.”

To identify the states with the greatest concentration of McDonald’s restaurants, 24/7 Wall St. reviewed location data for McDonald’s, Burger King, Wendy’s (NASDAQ: WEN), Taco Bell, KFC which is a division of Yum! Brands (NYSE: YUM), Subway, Starbucks (NASDAQ: SBUX), Pizza Hut, Dunkin’ Donuts (NYSE: DNKN), and Chick-fil-A from Menuism. Population data, income, and poverty statistics are from the U.S. Census Bureau’s 2013 American Community Survey (ACS). Also from the ACS, we included educational attainment rates, self-reported obesity rates, and the percentage of the population without health insurance. We also considered the percentage of the population with low access to major food stores from the USDA’s Food Atlas.

These are the states with the most McDonald’s outlets per 100,000 residents.

10. Kentucky
> McDonald’s locations per 100,000 residents: 5.94
> Obesity rate: 33.2% (5th highest)
> Pct. consuming vegetables less than daily: 25.2% (15h highest)
> Median household income: $43,399 (5th lowest)

There are nearly six McDonald’s restaurants per 100,000 Kentucky residents, the 10th-highest ratio in the country. As in other states with relatively high numbers of McDonald’s stores, Kentucky is also home to more than 100 Wendy’s locations, or 3.5 stores per 100,000 residents — the 4th highest rate nationwide. Fast food tends to be far more affordable than other restaurant fare, and residents in low-income states are perhaps more likely to visit a McDonald’s. A median household in Kentucky earned $43,399 in 2013, less than all but a handful of other states. Residents were also not as educated as the average American — less than 23% of adults had at least a bachelor’s degree, one of the lowest educational attainment rates in the country. A high prevalence of fast food restaurants is often representative of a poor food landscape, in which many people struggle to access healthy foods. Nearly 46% of Kentucky residents reported consuming fruits less than once daily, the seventh-highest percentage nationwide. Roughly one-third of Kentucky residents were obese, one of the highest obesity rates in the country.

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9. Indiana
> McDonald’s locations per 100,000 residents: 5.97
> Obesity rate: 31.8% (9th highest)
> Pct. consuming vegetables less than daily: 27.3% (4th highest)
> Median household income: $47,529 (17th lowest)

Indiana has about 270 Burger Kings locations, or 4.1 per 100,000 residents. While this is the highest concentration of Burger Kings in the country, there are nearly 400 McDonald’s restaurants or about 6 per 100,000 residents, in the state. Subways are even more common, with more than 10 per 100,000 residents, making Subway more common in Indiana than in all but three other states. Without examining individual consumption habits, it is difficult to tie a high concentration of McDonald’s outlets to negative health outcomes. However, as in nearly every other state with the most McDonald’s restaurants, Indiana’s obesity rate of nearly 32% was among the highest nationwide. Also, 27.3% of residents reported consuming vegetables less than once daily, the fourth-highest percentage in the country.

8. Tennessee
> McDonald’s locations per 100,000 residents: 6.05
> Obesity rate: 33.7% (4th highest)
> Pct. consuming vegetables less than daily: 25.4% (14th highest)
> Median household income: $44,297 (9th lowest)

Tennessee’s roughly 6.5 million residents have access to numerous Burger King, Wendy’s and Taco Bell restaurants, each of which has more than 200 locations in the state. McDonald’s has nearly twice as many locations, 393, or 6.05 per 100,000 Tennesseans, the eighth-largest concentration in the country. As in other areas with relatively high numbers of McDonald’s stores, and particularly those in the Southern United States, Tennessee residents had low incomes and reported relatively poor health outcomes. A typical household in the state earned $44,297, one of the lowest median annual household incomes in the nation. And nearly 34% of residents were obese, the fourth-highest obesity rate in the country.

7. Missouri
> McDonald’s locations per 100,000 residents: 6.10
> Obesity rate: 30.4% (16th highest)
> Pct. consuming vegetables less than daily: 25.2% (15th highest)
> Median household income: $46,931 (14th lowest)

There are 6.1 McDonald’s restaurants per 100,000 Missouri residents. The frequency of Taco Bells in the state is also more than any other state, and the frequency of Pizza Huts is the sixth-highest. Missouri’s 30.4% obesity rate in 2013 was among the higher rates. As in other states with high numbers of fast food restaurants, Missouri residents reported relatively poor eating habits. Almost 44% of residents reported consuming fruit less than once a day, the 9th highest percentage nationwide. This may be due to relatively poor access to healthy foods, and low incomes. The median household earned an annual $46,921, one of the lowest figures. And about 60% of food programs in Missouri reported an increase in the number of clients in 2014 compared to 2013. Missouri residents also reported poor health outcomes, with a relatively high rate of cardiovascular deaths, 281 per 100,000 residents, the 10th-highest in the nation.

6. Arkansas
> McDonald’s locations per 100,000 residents: 6.21
> Obesity rate: 34.6% (3rd highest)
> Pct. consuming vegetables less than daily: 28.6% (3rd highest)
> Median household income: $40,511 (2nd lowest)

McDonald’s provides famously inexpensive food, and lower-income Arkansas residents may frequent the restaurant and other fast food locations. Arkansas had the second-lowest median household income in the country in 2013, $40,511, and the third-highest poverty rate, 19.2%. There are 6.2 McDonald’s locations per 100,000 residents in the state, the sixth-highest concentration in the country. In addition, there are 3.4 Taco Bells and 2.6 KFCs per 100,000 residents — each the second-highest ratios nationwide. About 34.6% of Arkansas residents were obese, the third-highest rate in the nation. Arkansas also has 9.3 Subways per 100,000 residents, one of the higher concentrations in the country. Although a significant portion of Subway ingredients, including bell peppers and tomatoes, are grown at Triple M Farms in Hamburg, Arkansas, relatively high percentages of state residents reported consuming fruit or vegetables less than once a day.

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5. Louisiana
> McDonald’s locations per 100,000 residents: 6.30
> Obesity rate: 33.1% (6th highest)
> Pct. consuming vegetables less than daily: 32.5% (the highest)
> Median household income: $44,164 (8th lowest)

There are 6.3 McDonald’s restaurants and 4.1 Burger Kings per 100,000 residents in Louisiana, the fifth- and second-highest rates, respectively, in the country. Louisiana had the fourth-highest poverty rate in the country at 19.1% and the eighth-lowest median household income, $44,164. Louisiana also had some of the lowest educational attainment rates in the country in 2013. About 83.1% of residents had at at least a high school diploma, and 22.5% had at least a college degree, each the fourth-lowest rates in the country. The prevalence of fast food restaurants is often representative of poor food landscape, in which residents often do not have easy access to healthy foods. This, in turn, can increase the likelihood of negative health outcomes. About one-third of Louisiana residents were obese, a rate exceeded by only five other states. Further, the state’s residents had among the highest rates of diabetes, high blood pressure and high cholesterol. In addition, Louisiana’s death rates from heart disease and cancer are among the highest in the country

4. Maryland
> McDonald’s locations per 100,000 residents: 6.33
> Obesity rate: 28.3% (22nd lowest)
> Pct. consuming vegetables less than daily: 22.8% (25th lowest)
> Median household income: $72,483 (the highest)

Maryland residents are exceptionally wealthy compared to other states with the most McDonald’s locations. The median household in Maryland earned $72,483 in 2013, the highest income in the nation. Residents were well educated, with more than 37% of adults having attained at least a bachelor’s degree, the third-highest rate in the country. There were three Starbucks stores per 100,000 Maryland residents, the eighth-highest proportion and exceptionally high compared to other states with the most McDonald’s. McDonald’s, as well as many other fast food restaurants, is popular among customers looking for inexpensive food, but high incomes in Maryland have not prevented numerous fast food restaurants from opening throughout the state. Chick-fil-A, KFC, and Wendy’s are all also quite common. Unlike most states with large numbers of McDonald’s restaurants, Maryland residents reported relatively healthy habits and outcomes, with better-than-average fruit and vegetable consumption, and an obesity rate of 28.3% — one of the lower percentages in the country.

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3. Kansas
> McDonald’s locations per 100,000 residents: 6.36
> Obesity rate: 30.0% (19th highest)
> Pct. consuming vegetables less than daily: 22.2% (19th lowest)
> Median household income: $50,972 (24th lowest)

An estimated 26.4% of Kansas residents had little access to grocery stores in 2010, the ninth-highest percentage in the country. This might help explain the prevalence of fast food restaurants in the state. Fast food chains thrive in Kansas. The state leads the nation with 39 major fast food chain restaurants for every 100,000 residents. McDonald’s, Burger King, Wendy’s, Taco Bell, Subway, and Pizza Hut are all among the most common in Kansas compared to other states. About 30% of Kansas residents were obese, tied with Pennsylvania and ahead of 30 other states. Kansas, a major U.S. beef producer, supplies McDonald’s

2. Michigan
> McDonald’s locations per 100,000 residents: 6.38
> Obesity rate: 31.5% (11th highest)
> Pct. consuming vegetables less than daily: 23.2% (23rd highest)
> Median household income: $48,273 (20th lowest)

Michigan has about 6.4 McDonald’s restaurants per 100,000 residents. The state is one of the most popular for fast food chains. In addition to McDonald’s, Michigan is in the top 10 for the number of Burger King, Wendy’s, Taco Bell, KFC and Subway locations per 100,000 residents. McDonald’s and other fast food restaurants are often frequented by customers looking for affordable food. As in many other states with the most McDonalds, Michigan had a relatively high poverty rate of 16.8%. High concentrations of fast food restaurants are also tied to relatively poor health outcomes. Michigan’s obesity rate, 31.5%, was higher than all but 10 states, and its heart disease death rate was higher than all but seven states.

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1. Ohio
> McDonald’s locations per 100,000 residents: 7.10
> Obesity rate: 30.4% (16th highest)
> Pct. consuming vegetables less than daily: 26.0% (12th highest)
> Median household income: $48,081 (19th lowest)

Ohio has more McDonald’s restaurants, 7.1 per 100,000 residents, than any other state and almost twice as many as Burger King’s 3.7 locations per 100,000 residents. There are far fewer McDonald’s outlets than Subways, which has 10.9 shops per 100,000 residents, more than in any other state. Ohio has the second-highest concentration of all major fast food restaurants. Only 15 states had an obesity rate higher than Ohio’s 30.4% in 2013. Ohio also has among the highest cardiovascular and cancer death rates, 274.6 per 100,000 and 207.7 per 100,000 respectively. Ohio has one of the two McDonald’s still serving pizza that were introduced more than 30 years ago. McPizza is still sold at a McDonald’s outlet in Pomeroy, Ohio. The other McDonald’s that sells pizza is about an hour away, in Spencer, West Virginia. In all other outlets, McDonald’s abandoned pizzas about 10 years after they were introduced because of their longer cook times.

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