Many key battlegrounds involve issues where traditional religious ideas clash with modern notions of sexuality, such as abortion, homosexuality and contraception.
The culture wars have been simmering since the 1960s, but the phrase was popularised by the sociologist James Davison Hunter in 1991.
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A year later, a speech by firebrand politician Patrick Buchanan to the Republican National Convention, in which he described a religious war for the soul of America, famously became known as the "culture war speech".
In it, he identified issues such as gay rights, pornography, abortion and discrimination against religious schools as "not the kind of change we can abide in a nation that we still call God's country".
Buchanan said: "This election is about much more than who gets what. It is about who we are. It is about what we believe.
"It is about what we stand for as Americans.
"There is a religious war going on in this country.
"It is a cultural war, as critical to the kind of nation we shall be as was the Cold War itself, for this war is for the soul of America."
The worst manifestations of the culture wars have seen violence directed towards abortion providers, with at least eight doctors, receptionists and security guards killed in such attacks in America over the past two decades.
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Echoes of US 'culture wars' between liberals and Christians