At the back of Evergreen Cemetery in Leadville, Colorado, lies a section where many bodies are buried without any markers. There are rows and rows of graves, but the only hint of what lies below is often just a body-length depression in the ground. This area is labeled the “Old Catholic” section of the cemetery. The dead were mostly miners, their wives, and children — immigrants, primarily. Many of these families settled first on the East Coast, then traveled to Colorado during the silver boom that began in the 1870s. They were part of the enormous wave of Irish who arrived in the United States in the years following the catastrophe known in Ireland as an Gorta Mór, or the Great Hunger.

James Walsh, an associate professor of political science at the University of Colorado, Denver, has devoted years of his life to resurrecting the lost history of immigrants to the West. He estimates that the Old Catholic section of the Evergreen Cemetery holds around 1,500 bodies, and perhaps two-thirds were Irish. Many belonged to the second generation of survivors of the Great Hunger — their parents lived through that calamity, while they survived the struggles that followed, including additional crop failures that took place during the 1870s.

This summer, with the help of interns who traveled to Denver from Ireland to assist with his research, Walsh and his team pored over records from the cemetery, nearby churches, the census, and newspaper archives to determine the identities of as many of the cemetery’s unnamed as possible. They discovered that 48% of those buried in the Old Catholic section were infants or children, and the average age of the dead was about 21.

Under what circumstances did an American community bury so many of its children?

There are almost no first-person accounts of the famine from the point of view of someone who went hungry. Survivors were often reluctant to discuss what had happened, if they were so lucky as to make it through alive. When the catastrophe hit, Ireland had been under British rule for seven centuries, during which time Catholics had seen their lands confiscated and laws passed that discriminated against them sharply. Millions of Irish were eking out a living as tenant farmers. The diet of the average tenant farmer consisted of 12 pounds of potatoes per day, plus buttermilk. In rural areas, people spoke primarily Gaelic, and few knew how to read or write — many had never been to school.

There was no Anne Frank to record the famine experience. And because of the wholesale erasure of history that happens during a massive dislocation, today Irish Americans know too little about their own ethnic group’s history. We have a hazy sense it has something to do with potatoes, but the rest of the story, like the graves in the Evergreen Cemetery, is missing all the particulars. Historians seeking to resurrect what happened to poor families during the famine and after they fled can trace the outlines of the drama through official sources but have found few vernacular accounts.

Walsh and his team were able to determine the names and ages of many of the families buried in Evergreen Cemetery, as well as the towns in Ireland they were from, but that is pretty much it. A large percentage of the Irish who made it to Leadville came from Cork, Walsh learned, and many had worked in copper mines on the Beara Peninsula.

Botanists have supplied additional revelations: Six years ago, scientists working from 150-year-old dried leaves successfully identified the genome of the organism that caused so much devastation. Phytophthora infestans, the late blight that decimated potato crops around the world, has often been called a fungus but turns out to be more closely related to brown algae.

Potatoes arrived in Ireland in the 1500s by way of Spanish conquistadores. The Spanish had discovered that staple in the Andes and brought it back to Europe. From Spain, the potato traveled to the Netherlands, a center of the plant trade, and from there to England and to Ireland. By the 1800s, Ireland’s tenant farmers had grown heavily dependent on one type of potato in particular, a large white variety known as the Irish lumper. The country’s population had swelled to 8 million, while the tracts owned by individual families had been divided and subdivided into ever-smaller slivers, and potatoes were all they could grow on such small plots of land.

The blight also traveled from the New World to the Old following a similar path. Botanists have wondered if Phytophthora infestans originated in the Andes, like the plant that it prefers to attack, but the first place where they know it appeared for certain is Mexico. The blight traveled to Philadelphia and New York, causing crop failures in those locations, then moved to the Netherlands, along with a shipment of seed potatoes. It soon struck in England as well. In the fall of 1845, there was consternation in Ireland about whether the blight might spread, but the new potatoes looked fine when harvested. The rest of the plants appeared robust, and there was talk of a plentiful harvest. But the late blight was devouring the remaining tubers underground, and when farmers dug up the rest of the crop, they found only a smelly mush. When they checked on their stores of new potatoes, those were rotting too.

The algae thrived in Ireland’s moist climate. In 1846, seed potatoes that carried the pathogen were put into the ground, and there was a total crop failure. Mass starvation began. The entire crop failed again in 1847, and huge numbers of people fell prey to typhoid and dysentery. People sold their animals, their furniture, everything. The most destitute wandered the streets naked, having hawked their clothing. Landlords evicted tenants who could not meet their rents, creating homeless by the thousands. People starved or died of fever or left at such a rate that the Irish population was swiftly reduced by a quarter. One million succumbed to famine or disease, and another million emigrated. Premature deaths and constant emigration continued even after the worst of the famine years. Thus began the great Irish diaspora.

Passage to Canada was cheaper than passage to the United States, and the Irish fled to both places. They arrived emaciated and penniless. Officials in New York City attempted to turn away boatloads feared to be bringing contagious diseases, but the Irish landed elsewhere and migrated to New York anyway. Soon they made up a quarter of that city, and the same quickly became true in Boston, Philadelphia, and Baltimore. In tenements and in cellars, they crowded together, 10 or 20 to a room. So many came at once that in the rare letters which have survived, writers warn kin back in Ireland that their own influx had caused a depression in wages along the East Coast. After word of the gold and silver rushes reached city slums, the most adventurous headed westward, settling in places like Butte, Montana, as well as San Francisco and Leadville.

The Irish who flocked there were willing to toil underground with the dream of striking it rich, but instead they died in appalling numbers. Walsh lists the causes of death as malnutrition, disease, altitude sickness, and the mining industry’s terrible working conditions, which caused many accidents.

Today it seems more important than ever to remember that when the Irish arrived in greatest numbers, we came without skills or resources. Many famine survivors harbored so much shame about the dissolution of their communities that they considered the past better left undisclosed, handing down to later generations only a partial understanding of the famine years. Even historians struggle as they attempt to recover what we have forgotten. This inability to know the past leaves Irish Americans frequently ignorant about their own ethnic group’s trajectory.

Kevin McAleenan, who has been the acting secretary of homeland security since April, told the New York Times that his father's family “was part of the Irish migration in the 1840s.” Last week, he spearheaded the Trump administration’s push to deny full citizenship to immigrants who seek public benefits, and this week he spoke favorably about overturning a court ruling that limits how long his agency can detain migrant children, arguing for indefinite detention.

Irish newspapers have taken to referring to Trump’s hard-right Irish American appointees as “alt-Irish,” so at odds are they with opinions about refugees and immigrants held in Ireland. It would be a preposterous irony for an administration with a long list of Irish Americans in its upper echelons to enact policies that penalize immigrants for arriving in the United States poor and hungry.

Do Irish American leaders really want to punish recent arrivals for accepting food stamps? When we first came in large numbers, we were at least as desperate as anybody who has arrived lately. But we don’t acknowledge that; we don’t notice all the unmarked graves at the back of the cemetery; we don’t ask who lies there, memorialized only by a dip in the ground. It is time to learn our own story, even if it is difficult to uncover. The long saga of the great Irish diaspora cannot end with us, of all people, being the ones to say that because you have suffered, you are not welcome. We long ago forfeited any right to close that particular door.