From Romania to Nepal, they call it the "golden ticket", a diversity visa lottery that offers citizens of countries with low immigration rates a chance to come to the United States.
Homeland Security officials say the programme was the entrance portal for Sayfullo Saipov, a 29-year-old man from Uzbekistan who is accused of mowing down pedestrians and cyclists on a Manhattan bike path, killing eight.
President Donald Trump - who along with some Republican lawmakers had previously called for ending the Diversity Visa lottery programme - doubled down, saying before a Cabinet meeting, "We need to get rid of the lottery programme as soon as possible."
"We are fighting hard for Merit Based immigration, no more Democrat Lottery Systems," the President tweeted.
Created in 1990, the programme issues up to 50,000 visas a year to people from dozens of countries. The aim is to mix up the nation's melting pot, although the visas are a tiny fraction of the roughly 1 million green cards the government issues annually.
"The terrorist came into our country through what is called the 'Diversity Visa Lottery Program,' a Chuck Schumer beauty," Trump tweeted as a jab at Senate Minority Leader Charles E. Schumer (D-N.Y.), who helped create the programme. "I want merit based."
The lottery is unusual because it does not require foreigners to obtain a sponsor - such as an employer or a relative - to come to the United States. Originally conceived as a way to help Irish citizens fleeing an economic crisis back home, the only requirement is that entrants be adults with a high school diploma or two years of recent work experience. Winners can bring their spouses and minor children. There is no application fee.
Millions apply each year. Fewer than 1 per cent are randomly selected to undergo background checks and receive a green card, which grants them permanent residency in the United States and puts them on a path to American citizenship. There were 11,391,134 applicants in fiscal 2016, the most recent data available.
The lottery has attracted legions of immigrants from dozens of nations, notably in Africa and Eastern Europe, which account for two-thirds of the lottery winners in recent years. Countries that have sent at least 50,000 people to the United States in the past five years - such as Brazil, Canada, China and Mexico - cannot participate.
The lottery, which has been managed by the State Department since it began in 1995, has raised concerns in the past, including in a 2007 Government Accountability Report that said it was vulnerable to scams. The report also cited concerns from federal officials that the lottery was open to applicants from countries whose governments are sponsors of terrorism.
Hesham Mohamed Ali Hedayet, who shot and killed two people at Los Angeles International Airport on July 4, 2002, came to the United States from Egypt through his wife, a visa lottery winner. Mohamed Atta, another Egyptian and one of the September 11, 2001, suicide pilots, applied for the lottery twice before entering the United States on a different visa to study aviation.
Supporters say the lottery enhances the nation's diversity and counters the idea that the United States is shutting its doors to foreigners. For immigrants, it is a random, life-changing experience that offers them opportunities beyond their dreams.
Winners undergo intense vetting before they can come to the United States. In the 2007 report, the Government Accountability Office suggested improvements to the programme but "found no documented evidence that DV immigrants from these, or other, countries posed a terrorist or other threat".
"It's a really good way of getting people that are otherwise not coming. It's such a small thing," said Muzaffar Chishti, director of the New York office of the Migration Policy Institute. "Diversity is a value in itself."
In 2013, the Senate immigration bill would have ended the programme in exchange for legal residency for millions of undocumented immigrants already in the United States. A bill proposed in August that would slash legal immigration levels in half over a decade also would eliminate the lottery programme.
The fiscal 2019 visa lottery is currently taking applications, with a deadline of noon Eastern time on November 22. Winners are scheduled to be chosen in May 2018.