A curious anniversary passed quietly last month. Just 110 years ago, on April 17, 1907, Ellis Island had the busiest day in the history of American immigration. European settlers had been arriving on the East Coast of the continent for 300 years by then — and, of course, all kinds of immigrants have been coming ever since. So why did this one day surpass all others, and by a lot? What's more, how does immigration policy then compare to now?

We took a tour of Ellis Island in search of answers.

Our guide was National Park Service Ranger Doug Treem, a basso profondo enthralled with the 62-year story of immigration into New York Harbor.

"That doorway right there," he said to start the tour, "is the single most important location of the 20th century." He was pointing to the extra-wide entryway at the top of the main steps to Ellis Island's Great Hall, where more than 12 million immigrants passed through on their way to American citizenship.

Hyperbolic? Yes. But Treem can't contain his enthusiasm when it comes to describing the island at its busiest in the years around 1907.

By then, New York's immigration station was a robust machine for moving people through it, most of them heading onto trains fanning out toward other parts of the country. Others crossed the harbor looking to dive into ethnic enclaves around the city.

The ill or infirm were admitted to a hospital on the island. Most of them healed, came back to the Main Hall for re-examination, and then passed through. But about 1 percent of immigrants were refused entry on the grounds of ill health or ideological undesirability, such as a professed devotion to anarchy, especially in the years after President William McKinley was shot dead by one in 1901.

So there's the first clue about how to set a single-day record in immigration: be an industrial-sized complex devoted to that single task and be operating at peak proficiency, as Ellis Island was in the spring of 1907. 

George Tselos, the supervisory archivist at Ellis Island, said the main factor behind the surge in numbers was a combination of powerful forces both pushing and pulling immigrants toward these shores. Europe was the source of most immigrants at the time, and Europe had problems: economic crisis in some countries, pogroms in others. That was the push. "Sizable number of Jewish immigrants decided in desperation that there was no future for them in Poland, Romania, and the old Czarist empire in the Ukraine," Tselos said. "Whole families emigrated."

The pull came from a boom in the American economy in the years before and up through the middle of 1907. Tselos said there was a very hot market for what immigrants had to offer. "America was a growing country in dire need of manual labor," he said. "It was only later that Congress decided those numbers of laborers were no longer needed when it passed the Quota Act in 1924."

But on April 17, 1907, it was all systems go. On that ordinary Wednesday, 11,747 immigrants passed through Ellis Island. Given the current political reality, it's a record not likely to be broken soon.