MONTGOMERY, Ala. — In a plain brown building sits an office run by the Alabama Board of Pardons and Paroles, a place for people who have been held accountable for their crimes and duly expressed remorse. Just a few yards up the street lies a different kind of rehabilitation center, for a country that has not been held to nearly the same standard.

The National Memorial for Peace and Justice, which opens Thursday on a six-acre site overlooking the Alabama State Capitol, is dedicated to the victims of American white supremacy. And it demands a reckoning with one of the nation’s least recognized atrocities: the lynching of thousands of black people in a decades-long campaign of racist terror.

At the center is a grim cloister, a walkway with 800 weathered steel columns, all hanging from a roof. Etched on each column is the name of an American county and the people who were lynched there, most listed by name, many simply as “unknown.” The columns meet you first at eye level, like the headstones that lynching victims were rarely given. But as you walk, the floor steadily descends; by the end, the columns are all dangling above, leaving you in the position of the callous spectators in old photographs of public lynchings.

The magnitude of the killing is harrowing, all the more so when paired with the circumstances of individual lynchings, some described in brief summaries along the walk: Parks Banks, lynched in Mississippi in 1922 for carrying a photograph of a white woman; Caleb Gadly, hanged in Kentucky in 1894 for “walking behind the wife of his white employer”; Mary Turner, who after denouncing her husband’s lynching by a rampaging white mob, was hung upside down, burned and then sliced open so that her unborn child fell to the ground.

There is nothing like it in the country. Which is the point.
“Just seeing the names of all these people,” said Bryan Stevenson, the founder of the Equal Justice Initiative, the nonprofit organization behind the memorial. Many of them, he said, “have never been named in public.” Mr. Stevenson and a small group of lawyers spent years immersing themselves in archives and county libraries to document the thousands of racial terror lynchings across the South. They have cataloged nearly 4,400 in total.

Inspired by the Holocaust Memorial in Berlin and the Apartheid Museum in Johannesburg, Mr. Stevenson decided that a single memorial was the most powerful way to give a sense of the scale of the bloodshed. But also at the site are duplicates of each steel column, lined up in rows like coffins, intended to be disseminated around the country to the counties where lynchings were carried out. People in these counties can request them — dozens of such requests have already been made — but they must show that they have made efforts locally to “address racial and economic injustice.”

Assumptions:
Each 12 foot tall steel column is a rectangular prism, with a volume of 24 cubic feet. Steel is mostly composed of iron and carbon (carbon represents 4% of its mass). The chemical formula for one steel molecule is Fe3C.
The mass of 1 cubic foot of steel is 490lbs.

9. If the depth of each column is one half its width, what are the dimensions (length, width and depth) of each column?

10. How much iron was used to make one column?

11. How much carbon (in pounds) was used in the entire memorial?