[_petronius]

Being undocumented is a civil offense, not a criminal one. The distinction is relevant, and important.

[caseysoftware]

US Code appears to disagree:

8 U.S. Code § 1325 - Improper entry by alien

(a)Improper time or place; avoidance of examination or inspection; misrepresentation and concealment of facts

Any alien who (1) enters or attempts to enter the United States at any time or place other than as designated by immigration officers, or (2) eludes examination or inspection by immigration officers, or (3) attempts to enter or obtains entry to the United States by a willfully false or misleading representation or the willful concealment of a material fact, shall, for the first commission of any such offense, be fined under title 18 or imprisoned not more than 6 months, or both, and, for a subsequent commission of any such offense, be fined under title 18, or imprisoned not more than 2 years, or both.

Ref: https://www.law.cornell.edu/uscode/text/8/1325

[klipt]

Visa application forms are really long and complicated and it's easy to make a mistake somewhere. With some motivated investigation and sufficiently broad interpretation I expect you could accuse most foreign visitors of "misrepresentation and concealment of facts"

[nucleardog]

Not going to dig too far to try and find updated numbers, but as of 2014 about 2/3 of people who had entered the country illegally that year were people that overstayed their visa and the ratio had been on an upward trend for quite a while.

I'm sure you could torture that into applying to that situation, but at least on a very plain reading it doesn't sound like it applies generally to those people.

[TimorousBestie]

8 USC 1325 and 1326 represent a fraction of immigration cases, mostly Mexican or South American smuggling. There are many other categories of undocumented person.

[criddell]

Would that apply to dreamers (people who were brought into the US by their parents when they were minors)?

[antonymoose]

Depending on the circumstances, the mood of a Federal agent, and of a prosecutor it could be charged either civilly or criminally. The sibling comment explains this better than I could.

Stepping past the direct offense of being here, one must ask how are they supporting themselves financially? Assuming they are workers, they’re either not paying taxes (a crime) or stealing the identity of a citizen in order to fool an employer. Now they are at least paying taxes, but they’ve victimized a lawful resident or Citizen. This is far from a victimless crime, it took my mother two years to fully clear her name after this occurred to her identity. The IRS and credit agencies are not very understanding.

[FuriouslyAdrift]

Improper entry is a criminal offense (crossing the border illegally, etc.)... unlawful presence (overstaying a visa, etc.) is a civil offense.

[dataflow]

You should clarify what you mean by undocumented. "Oops I lost my passport somewhere" is very different from "I lack documentation because I crossed the border illegally."