During debates over immigration in the United States, a figurative line of immigrants waiting to obtain legal status is often invoked. Kansas Secretary of State Kris Kobach referenced this imaginary queue in his defense of President Trump’s decision to end the Deferred Action for Childhood Arrivals Program earlier this month. “I would suggest [to DACA recipients]: Go home and get in line, come into the United States legally, then get a green card, then become a citizen,” he said in an interview on MSNBC.

While Kobach’s description of this sequence isn’t wrong, the suggestion that there is a single “line” for legal status oversimplifies the process. Indeed, there are multiple lines, not one of which is simple to navigate, and some of which can take decades to get through depending on an individual’s circumstance.

As it stands, the maximum number of permanent immigrants permitted into the country annually is 675,000, with some exceptions. While their reasons to live in America vary widely, immigrants seeking permanent status usually must fulfill one basic requirement: that they enter—and reside in—the country legally. For the segment of the population that qualifies for DACA—those who were brought to the United States illegally as children—that often keeps them from applying. Even if an applicant has a sponsor, as all are required to have, he or she can still be impeded by the fact that they came in illegally.

“It doesn’t matter why you came in, it doesn’t matter how old you were, if you were a baby or a toddler, it doesn’t matter when it comes to these sets of laws,” Jeremy McKinney, an attorney and secretary of the American Immigration Lawyers Association, told me earlier this month. For the majority of DACA recipients, whose work permits are set to expire in the coming months, Congress passing a law is the only chance they have to gain legal status in the United States.

DACA beneficiaries aside, millions of immigrants meet the criteria to become lawful permanent residents in the United States, but are often subject to a long wait.  

The United States has a cap for how many people can apply for a visa from each country. There are three factors that determine who gets approved: what category an individual falls under, how many others are in that category, and when an individual applies. Certain types of people have to wait decades to apply for an immigrant visa, while others take a much shorter amount of time. A U.S. permanent resident’s unmarried son or daughter, who is 21 years old or older, will have to wait roughly 21 years to file an application for an immigrant visa if they’re from Mexico, according to the State Department’s visa bulletin. The delay is a result of too much demand.

“People have this mental image of a line, [and] it’s coming from somewhere—it’s coming from a kernel of truth, and the kernel of truth is in that visa bulletin,” McKinney said. “It’s the general line for everyone except the countries that have used all of their visas—and then, those lines are even worse.”

For those already in the United States on a non-immigrant visa—for example, as a student or employee—they can adjust their status to become lawful permanent residents. But that process, too, can take several years and is only available to some people.  

Judge Paul Schmidt, who was appointed in 2003 by Attorney General John Ashcroft and primarily served in the Arlington Immigration Court in northern Virginia before retiring, presided over these types of cases. “The basic requirement is that you have to be inspected at the border and admitted or paroled into the United States, and you have to be maintaining a legal status at the time you applied for adjustment of status, and you have to have not worked [without] authorization prior to filing for adjustment of status,” Schmidt said.

Individuals can remain in the United States as lawful permanent residents indefinitely, though they also have the option to pursue citizenship through naturalization, after residing in the country for a certain number of years. Military-service personnel are unique in that they are eligible for expedited naturalization. “If you are part of the military, any component of the military, during a time of hostilities, which has been in place since 9/11, then you’re eligible for citizenship,” McKinney said. Barring some exceptions, an individual must be a lawful permanent resident to join the military.

The Department of Homeland Security keeps records of how many immigrants have gained lawful permanent residence. According to the agency’s latest figures, 289,000 immigrants obtained this status in the first quarter of fiscal year 2017, along with 270,000 in the second quarter. Roughly half did so through their immediate relatives who are U.S. citizens. Approximately 13 percent qualified under an employment-based category.

Some Republicans have criticized the U.S. immigration system for admitting a large flow of foreign-born workers, who they argue take away job opportunities for Americans. Immigration hardliners, in particular, take issue with the family-based category. In August, Trump endorsed a bill drafted by Senators Tom Cotton and David Perdue that aims to cut legal immigration by 50 percent over a decade. While the introduction of the legislation is significant, it’s unclear whether it’ll gain traction in Congress, leaving in place the current immigration system and the “line” that’s emblematic of it.