The Civil War lessons taught to American students often depend on where the classroom is, with schools presenting accounts of the conflict that vary from state to state and even district to district.
Some schools emphasize states' rights in addition to slavery and stress how economic and cultural differences stoked tensions between North and South. Others highlight the battlefield acumen of Confederate commanders alongside their Union counterparts. At least one suggests that abolition represented the first time the nation lived up to its founding ideals.
The differences don't always break down neatly along geographic lines.
"You don't know, as you speak to folks around the country, what kind of assumptions they have about things like the Civil War," said Dustin Kidd, a sociology professor at Temple University in Philadelphia.
Lessons on the war and its causes usually begin in the fifth through eighth grades. That means attitudes toward the war may be influenced by what people learned at an age when many were choosing a favouritecolour or imagining what they wanted to be when they grew up.
The effect may not be obvious until a related issue is thrust into the spotlight like this month's violence in Charlottesville, Virginia, and the resulting backlash against Confederate symbols.
Growing up in Charlottesville, Kidd said, he was taught that "folks from the North" had put forward the "misconception" that slavery was the cause of the war. The real origin, he was told, could be traced to groups of colonists from England who despised each other long before the rebellion began in 1861. Not until graduate school did he begin to question that premise.
Confederate sympathizers have long promoted the "Lost Cause" theory that the Southern side was heroic against impossible odds, and that slavery was not the driving force behind the war. Edward Countryman, a history professor at Southern Methodist University in Dallas, said he learned that idea growing up in New York state in the 1950s.
"I recall my father coming home when I was about 8 or 9 with two Civil War caps, one's grey and one's blue. And I wanted the grey one," Countryman said. "The belief, strongly, that the Civil War had been about anything but slavery was very, very powerful."
A 2011 Pew Research Center poll found that 48 per cent of Americans said the Civil War was mainly about states' rights, compared with 38 per cent who said its main cause was slavery. Nine per cent said both factors were equal.
The divide in opinions broke down more by race than geography. Forty-eight per cent of whites chose states' rights over slavery, while 39 per cent of blacks did. But 49 per cent of self-described Southern whites chose states' rights compared with 48 per cent of whites who did not consider themselves Southern.
The president of the Texas NAACP said finding "kinder" ways to describe the war's origins masks racism.
"States' rights is about the whole idea of permitting slavery and allowing the South to do what they do, or, after slavery, to allow the South to engage in Jim Crow," Gary Bledsoe said. "You can't sanitize history and have history report that master and slave were out there singing 'Kumbaya' in the fields."
Texas has 178 confederate monuments. Only Virginia has more, with 223, according to the Southern Poverty Law Center, a civil rights advocacy group.
Democratic state Rep. Eric Johnson, meanwhile, is demanding the removal of a nearly 60-year-old plaque rejecting slavery as the Civil War's "underlying cause." Republican House Speaker Joe Straus has called for checking the accuracy of that plaque and nearly a dozen other Confederate symbols located around the state capitol alone.
When curriculum standards were approved in 2010 by Texas' Republican-controlled Board of Education, debate focused on slavery being a Civil War "after issue."
The state's fifth- and seventh-graders taking Texas history courses, and eighth-graders taking U.S. history, are now asked to identify the causes of the war, "including sectionalism, states' rights and slavery."
Eighth-graders also compare ideas from Abraham Lincoln's inaugural address with those from Confederate President Jefferson Davis' inaugural address, which did not mention slavery and instead endorsed small-government values still popular with many conservatives today.
The eighth-grade curriculum also lists Confederate Gen. Thomas "Stonewall" Jackson alongside Frederick Douglass, a 19th century abolitionist, as examples of "the importance of effective leadership in a constitutional republic."
Home to about 5.3 million public school students, Texas has a textbook market so large that volumes published for its classrooms can be sold in other states, though that influence has waned recently. Publishers can now more easily tailor electronic materials to the needs of individual markets.
Still, in 2015, a publisher promised to make editorial changes after a mother in Houston complained that her son's ninth-grade geography textbook referred to African slaves as "workers" and immigrants."
Virginia's standards of learning for U.S. history to 1865 include "describing the cultural, economic and constitutional issues that divided the nation" and "explaining how the issues of states' rights and slavery increased sectional tensions." Alabama fifth-graders "identify causes of the Civil War from the Northern and Southern viewpoints."
Contrast that with Delaware, where school districts set their own curriculum but a syllabus for the eighth grade suggesting what might be covered during instruction says that abolition meant that the American people could for the first time "seriously claim to be living up to their commitment to the principle of liberty rooted in the American state papers."
In Michigan, curriculum also is decided locally, though the state's social studies standards for the Civil War and Reconstruction in eighth grade include the instructions: "Explain the reasons (political, economic, and social) why Southern states seceded and explain the differences in the timing of secession in the Upper and Lower South."
Massachusetts' framework for a U.S. history course asks students to "describe the rapid growth of slavery in the South after 1800 and analyze slave life and resistance on plantations and farms across the South."
Chester Finn, president emeritus of the conservative Thomas B. Fordham Institute, an educational non-profit, called teaching history and social studies "a real jigsaw puzzle" since many states leave standards up to school districts.
Still, "If the state curriculum calls it the 'War of Northern Aggression' and says states' rights were dominated by the Yankee army crushing the good people of the South, and slighting the whole slavery issue," Finn said, "you can influence what a million kids take away."