Ellis Island
The New York harbor station where 12 million immigrants were inspected, tagged, and admitted or turned back between 1892 and 1954.

Roughly 40 percent of Americans alive today can trace at least one ancestor through a single building in New York harbor. Ellis Island opened on January 1, 1892, and by the time it closed in 1954 it had processed more than 12 million arrivals. It was not a welcome center. It was a filter, built to decide, at a rate of thousands per day, which human beings the United States would keep.
Six seconds
The immigrants who mattered here were the ones traveling in steerage. First and second class passengers were inspected in their cabins and walked off at the Manhattan piers; only the poor were ferried to the island. There they climbed a staircase into the Registry Room, and the climb was itself the first test, because doctors stood at the top watching for anyone short of breath, limping, or struggling with a bag.
The medical inspection that followed took a matter of seconds. Inspectors chalked letters on the coats of anyone who needed a closer look: L for lameness, H for a suspected heart condition, X for a suspected mental defect, E for eyes. The eye check was the one arrivals dreaded, because it meant an inspector flipping the eyelid back with a buttonhook to look for trachoma, a contagious and then largely untreatable infection that was grounds for exclusion. Then came the legal inspection, roughly thirty questions matched against the ship's manifest: name, occupation, destination, money in pocket, whether a job had been arranged in advance, which was itself disqualifying under contract-labor law.
Most people passed. About 2 percent were sent back, which sounds small until you consider it meant a quarter of a million rejections, and that families were sometimes split by it, one child held for a fever while the rest went on. Immigrants called the place the island of tears.
The gate opens and closes
The volume is difficult to imagine now. 1907 was the peak: over a million people came through in a single year, and on the busiest day more than 11,000 were processed. The great majority in this era came from southern and eastern Europe, Italians, Poles, Slovaks, Greeks, and Jews fleeing the Russian empire, and their arrival provoked exactly the argument the country has been having ever since: that these newcomers were too foreign, too Catholic or Jewish, too poor, too many.
That argument won in the 1920s. The Johnson-Reed Act of 1924 imposed national-origin quotas calculated to freeze the ethnic composition of the country, cutting arrivals from Italy and Poland to a trickle and barring most Asians entirely. It also moved the screening overseas, to American consulates, which made Ellis Island's inspection halls redundant almost overnight. The island spent its last three decades as a detention and deportation center, holding enemy aliens during two world wars and suspected radicals during the Red Scares, and closed in 1954.
It is worth remembering that Ellis Island was the generous door. On the West Coast, arrivals from Asia were processed at Angel Island in San Francisco Bay, where the Chinese Exclusion Act meant interrogations designed to catch people out and detentions that lasted weeks or months rather than hours. Some detainees carved poems into the barrack walls.
The building reopened in 1990 as a museum, and it now functions as a national origin story: the huddled masses, the tagged coats, the family name supposedly mangled by an inspector, a legend the records disprove, since manifests were written at the port of departure. The story it actually tells is more useful. A country can be built by immigration and be frightened of it at the same time, and the same nation that processed a million people in a year could, seventeen years later, decide it had had enough.