The Confederate battle flag flies outside the South Carolina Capitol the day before it was taken down in July. (Richard Ellis/EPA)

There is a consensus among historians that the root cause of the Civil War was slavery. But a lot of Americans don’t believe that’s true, and don’t believe that’s what children should learn in school, according to the results of a new poll.

Just over half of Americans say that slavery was the main cause of the Civil War, but 41 percent disagree, according to a McClatchy-Marist poll published Thursday.

Americans break in a similar way over what children should learn in school, with 55 percent saying they should be taught that slavery was the main reason for the war, and 37 percent disagreeing.

[Texas officials: Schools should teach that slavery was a “side issue" to the Civil War]

There are some differences by race, geography and age. Southerners, whites and those over 60 are less supportive than other groups of teaching that slavery was the main cause of the war. Democrats are more likely than Republicans and independents to say slavery should be taught as the primary cause.

But whatever those differences, at least a quarter of Democrats, African Americans and Northeast residents say schools should not teach students that slavery was the primary cause of the Civil War.

The division over what children should learn in school is clear in Texas, where academic standards list slavery third among the causes of the war, after sectionalism and states’ rights — written deliberately in that order to telegraph what some elected Texas officials described as slavery’s secondary role in driving the conflict.

Slavery was a “side issue to the Civil War,” said Pat Hardy, a Republican member of the State Board of Education, when the board adopted the standards in 2010. “There would be those who would say the reason for the Civil War was over slavery. No. It was over states’ rights.”

The results of the new poll are similar to a 2011 CNN/ORC poll finding that 54 percent of Americans said keeping slavery legal was the main reason Southern leaders led their states to secede from the United States, while 42 percent said slavery was not the main reason. Other surveys that year, which asked whether states’ rights or slavery was the main cause of the war, found more respondents choosing states’ rights as the reason.

The McClatchy-Marist poll was conducted July 22-28 among a random national sample of 1,249 adults reached on conventional and cellular phones. The margin of sampling error for overall results is plus or minus 2.8 percentage points.