An American child grows up in a married household in the suburbs. What are the chances that his family keeps a gun in their home?

The probability is considerably higher than residents of New York and other big cities might expect: about 40 percent of married households reported having a gun in their home, according to the exit poll conducted during the 2008 presidential election.

But the odds vary significantly based on the political identity of the child’s parents. If they identify as Democratic voters, the chances are only about one in four, or 25 percent, that they have a gun in their home. But the chances are more than twice that, almost 60 percent, if they are Republicans.

Whether someone owns a gun is a more powerful predictor of a person’s political party than her gender, whether she identifies as gay or lesbian, whether she is Hispanic, whether she lives in the South or a number of other demographic characteristics.

It will come as no surprise to those with a passing interest in American politics that Republicans are more likely to own guns than Democrats. But the differences have become much more stark in recent years, with gun ownership having become one of the clearest examples of the partisan polarization in the country over the last two decades.

In 1973, about 55 percent of Republicans reported having a gun in their household against 45 percent of Democrats, according to the General Social Survey, a biennial poll of American adults.

Gun ownership has declined over the past 40 years — but almost all of the decrease has come from Democrats. By 2010, according to the General Social Survey, the gun ownership rate among adults that identified as Democrats had fallen to 22 percent. It remained at about 50 percent among Republican adults.

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The 2008 poll makes clear that gun ownership is deeply embedded in political identity, and vice versa. (Unfortunately, the question on gun ownership was dropped from the 2012 national exit poll.) Some other variables, like race or where a voter lives, also strongly predict gun ownership. But the differences between the parties remain even after accounting for these characteristics.

White voters were substantially more likely to own guns than Hispanics or blacks. But white Republicans were more likely to own guns than white Democrats.

And based on demographic inertia, the differences seem likely to grow over time.

About 35 percent of Democratic voters age 65 and older reported having a gun in their home, against about 25 percent of those ages 18 to 29. But gun ownership rates bore little relationship to age among Republican voters, and were constant at about 55 percent among all age groups. That might suggest that gun ownership will continue to decline among Democrats while holding steady among Republicans, further increasing the partisan gap.

Gun ownership rates are highest in rural areas, where guns are more likely to be used for hunting as well as personal protection. A slight majority of Democratic voters in rural areas said they had a gun in their home, according to the survey, although the rate was somewhat higher, 65 percent, among rural Republicans.

In urban areas, 40 percent of Republican voters said they had a gun in their home, while 20 percent of Democrats did.

The differences are most apparent in suburban areas. There, 58 percent of Republican voters said there was a gun in their household, against just 27 percent of Democrats.

Having school-age children in the household did not significantly affect gun ownership rates, either positively or negatively. A majority of Republican-voting parents of minor children had a gun in their home, while only about one in four Democratic-voting parents did.

In other respects, the profile of gun owners defies some of the stereotypes that urban liberals might assign to them. For example, despite President Obama’s comments in 2008 about voters who “cling to guns and religion,” the two qualities are not strongly correlated. Slightly more than 40 percent of voters who said they attended church weekly or more often reported having a gun in their home, about the same percentage as among those who attend religious services just a few times a month or a few times a year. And gun ownership rates are highest among the middle class, rather than the poor. Households making $50,000 to $100,000 per year were slightly more likely to own guns than those that made a little bit less or a little more. (However, gun ownership rates are inversely correlated with educational attainment.)

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Perhaps last weekend’s mass shooting in Newtown, Conn., will serve to diminish the partisan split in attitudes toward guns; early polls on Newtown find relatively modest differences between Democrats and Republicans on what they see as the causes of the shooting. Then again, following the initial aftermath, the partisan divide in attitudes toward guns has seemed only to accelerate after similar past events, as at Columbine High School in 1999.

It might seem strange that ownership of a single household object is so strongly tied to voting behavior and broader political attitudes in America. But America is an outlier relative to other industrialized nations in its gun ownership rates. Whatever makes this country so different from the rest of the world must surely be reflected in the differences in how Democrats and Republicans see the nation.