President Trump is going to California on Tuesday with a message — not for Californians themselves, as his Attorney General Jeff Sessions did last week when he announced he was suing the state, but for the rest of America:

The border wall is real.

Trump’s visit to eight wall segment prototypes standing in Otay Mesa near San Diego is fundamentally a photo op. The president wasn’t intimately involved in the process of selecting the prototypes last summer, building them last fall, or testing them over the winter. But the process happened nonetheless — quietly, because Trump wasn’t talking about it.

To Trump’s critics, the wall is a punchline — every so often, someone will tweet, “Hey, remember when Mexico was going to pay for the wall?” and people will laugh appreciatively. In fairness, they’re taking cues from Trump himself, who — when he talks about the wall at all anymore — treats it with no more detail or seriousness than he does any other fanciful idea.

But there is more to the Trump administration than Trump himself. The president may be disengaged from the work of policy, but the officials he appointed and the civil servants under them are still chugging along to fulfill what they imagine as his mandate. And part of that mandate is that new physical barriers will be built at the border, and they will be called a wall.

Trump’s visit to see wall prototypes marks the end of a months-long process

The process of building a wall started weeks after the inauguration, when the Department of Homeland Security (DHS) put out requests for contractors to submit bids on two different projects.

One was for a border wall made of concrete, and the other was for a border wall made of “other materials”; the latter had to be something that border patrol agents would be able to see through. (When Trump alluded to the wall needing to be “see-through,” he was mocked widely, but he was actually echoing a demand made by border patrol agents themselves.)

In April, submissions closed; as many as 450 companies submitted bids.

In August 2017, the Department of Homeland Security announced that six contractors had been elected to build eight prototype segments (two contractors were selected to build both concrete and “other” wall models).

In October 2017, the prototypes were built in Otay Mesa, California.

In December 2017, the government started tests to see if the prototypes held up to the government’s demands for impenetrability. An unnamed official described the training to the Associated Press: “Military special forces based in Florida and U.S. Customs and Border Protection special units spent three weeks trying to breach and scale the eight models in San Diego, using jackhammers, saws, torches and other tools and climbing devices.”

In January, the government announced that the prototypes had all passed testing. An official told the AP that the best model would likely incorporate various prototype designs, but that a see-through wall — in the form of steel poles (also called bollards) topped by concrete — was the best overall design.

Fox News contributor Katie Pavlich claimed in March that “members of our Navy SEAL community” had been involved in testing efforts and hadn’t been able to breach the wall. She was wrong — the Navy says that no SEALs were involved in border wall testing — and was roundly mocked for it.

But many of the people mocking her may not have realized that she really wasn’t that far off — there were special forces involved in the testing, and the testing was in fact successful. Paying attention to the exaggeration allowed people to keep treating the wall as a fantasy instead of recognizing that an exaggeration about who tested wall prototypes meant there was something to test.

How much wall gets built will depend on Congress — but it won’t be “none”

Technically, the prototypes aren’t even the first “wall” the administration has built: Congress appropriated money to DHS to replace 16 miles of pedestrian fencing in California during the 2017 fiscal year (which ended on September 30), which the Trump administration replaced with a “steel bollard wall design.”

DHS had been using the steel poles called bollards to build border barriers for years, and calling a row of steel poles a “wall” rather than a “fence” might be a matter of nomenclature, but the point remains: Any money given to DHS for building physical barriers, or replacing existing barriers, could be used for something called a “wall” unless otherwise specified.

When the administration has tried to ask for extra money to build some wall — in a supplemental funding request for DHS in spring 2017, for instance, or in one of the short-term spending bills Congress has passed over the past six months — it’s been shot down.

But there’s a difference between including a provision just for wall money over and above everything else and giving the administration money for DHS to spend for an entire fiscal year. Congress is currently working on a funding bill to carry the government through the end of the fiscal year in September — and it will almost certainly include money for physical border infrastructure that can be called a “wall.”

How much money, and how many miles, is an open question. The Trump administration’s 2019 budget request for the Department of Homeland Security asked Congress for $1.6 billion to build 65 miles of wall, mostly in Texas. (Some of it will replace existing barriers, and some of it will be “levee wall” intended as a flood barrier as well as an anti-crossing measure.)

The budget the president asks for doesn’t always resemble the budget Congress ultimately gives him, so it’s not clear how much of that $1.6 billion he’ll ultimately get. But Trump is going to get something for physical border barriers — and just like the $341 million the Obama administration got for fence replacement fiscal year 2017 was used for a “wall,” any construction done with border infrastructure money in 2018 and beyond is liable to have the “wall” label slapped on it.

The smaller the wall gets, the realer it gets

Just budgeting for a wall isn’t the same as building one. There are plenty of legal and logistical obstacles, as previous administrations’ efforts to build border barriers have shown.

Property owners in Texas are fighting the government’s efforts to take their land through eminent domain to build a wall, just like many of them fought (and are still fighting) efforts made by the Bush administration to take their land to build a “secure fence” 10 years ago. Environmental laws prevent new construction in certain areas. Any contracting project — especially run by DHS — runs risks of drastically overshooting both its schedule and its budget.

But these aren’t obstacles to any sort of wall being built. At most, the eminent domain suits will prevent the administration from being able to build as close to the border as they would like along particular stretches, or force them to leave a gap in the barrier system. At least, they’re minor hurdles for the administration to jump over — federal Judge Gonzalo Curiel ruled in February that the Trump administration had acted legally when it gave itself an environmental waiver to build the prototypes Trump’s visiting this week.

To be clear, there is no way in hell that Donald Trump will leave office with a fully intact, 2,000-mile wall that stretches from the Pacific Ocean to the Gulf of Mexico. But even Trump all but stopped calling for that even before he was elected.

The government’s estimates for the ultimate length of the wall keep getting shorter. DHS proposed a 1,250-mile wall system in 2017; a January plan sent to Congress, as part of negotiations over a bill to address the status of unauthorized immigrants facing the loss of their protections under the Deferred Action for Childhood Arrivals (DACA) program, asked for $18 billion to build 700 miles over 10 years.

That might sound like a series of concessions; a whittling down to nothing. It’s actually the result of a process of asking DHS officials how a wall could be built — what it would take for a wall to become real.

That process will culminate in Trump’s visit Tuesday, at which he will doubtless take credit for the wall prototypes and conveniently forget that his ideas (solar power!) bore no relationship to the actual selections. The prototypes themselves don’t look terribly imposing or beautiful; they look utilitarian and kind of grubby. That’s what happens when fantasy turns into reality.

You don’t need a 2,000-mile wall to send a “keep out” message

If critics were concerned that Trump really would try to build a wall across the entire border, that concern has been safely assuaged. If they’re worried that the administration will waste billions upon billions of dollars for a physical barrier at a time when border crossings are still pretty low — and many of the people crossing are asylum seekers who aren’t trying to sneak in — those are fights that they can continue in Congress, as future appropriations determine how quickly and expensively the wall gets built.

But much of the concern about the wall is symbolic: that it’s a bad look to shut out one of the US’s two land neighbors (and the only one that isn’t majority white) with a physical barrier while bragging about how that barrier will keep out “bad hombres”; that it spits in the face of America’s “nation of immigrants” legacy and says something worrisome about the country’s place in the world.

Those concerns aren’t about how long the wall is or what it’s made of. They’re about President Trump standing next to something and bragging that the US has built a wall. They’re about, in other words, what Trump is going to do on Tuesday. And no matter how many miles actually get built, that message can’t be taken back.