Congress is jumping back into the immigration policy thicket as the House votes Thursday on two bills. One major bone of contention: President Trump’s proposed border wall. Debate about the wall will largely focus on practical matters, such as cost and effectiveness. But the most important line of argument is likely to be ignored: Societies that put up walls tend to fail.

Walls are endemic of larger problems, which are exposed by the walls themselves. Nowhere was this clearer than in East Germany. The infamous Berlin Wall signified the East German government’s determination to keep its population trapped, but another, lesser-known East German wall proved to be effective — and devastating.

The center of Mödlareuth, a tiny German farming village 200 miles southwest of Berlin, had been a boundary line since the 19th century, first dividing a German kingdom and principality, and after the 1871 establishment of the German nation-state, between the states of Bavaria and Thuringia. In the aftermath of World War II, the victorious Allies used it as the new border between the U.S. and Soviet zones of occupation. In 1949, as the Cold War hardened, it became the border between East and West Germany.

While massive international attention was focused on Berlin, the city was about 100 miles deep inside East Germany and West Berlin was essentially an island within that country. Mödlareuth, by contrast, had the unusual and unfortunate distinction of being directly on the new border between East and West Germany. Between 1952 and 1961, more than 2 million East Germans fled west, often to pursue lives with more opportunities, sometimes through or around Mödlareuth.

To help stop this exodus and to keep eastern villagers on their side of the Tannbach stream (which marked the boundary in Mödlareuth), in 1952, the East German government put up a wooden fence through the community. Over the next 14 years, East Germany gradually increased the border fortifications through and around Mödlareuth, laying mines and adding fences.

While the 1961 construction of the Berlin Wall made escaping to the capitalist, Western-allied West Berlin far more difficult, the 800-mile inner-German border remained vulnerable. So East Germany continued to try to fortify the boundary in Mödlareuth, culminating in 1966 with the construction of a far less famous, 2,300-foot-long, nine-foot-tall concrete wall. For the next 23 years, Mödlareuth, divided in half by this concrete bulwark, was known as “Little Berlin.”

Even after the wall was built, East German border troops worked to make escape more difficult. In 1970, they secretly installed the now infamous “Splittermine SM-70” mines along the frontier. Each mine consisted of a small metal bar mounted to a border barrier attached to a firing device shaped like a cone: when triggered by an attached tripwire, it fired shrapnel.

Despite the daunting nature of this security system, on May 25, 1973, a 34-year-old East German van driver wrapped up his regular Friday night card game at a nearby bar and set off for Mödlareuth, determined to commit a serious offense: Republikflucht, illegal flight from East Germany, a crime punishable by up to three years in prison.

He passed through multiple checkpoints in his company van, aided by a pass he had for work that allowed him into the restricted zone around the wall. He shared cigarettes with the two East German border troops on duty, remarking, “With these, the night won’t be so long for you.” Perhaps thanks to this gesture, the officers let him proceed, even though East German law forbade entrance into the “protection strip” between 11 p.m. and 5 a.m.

Once at Mödlareuth, the driver switched off the van’s headlights and drove up to the wall. He parked and climbed on top of the van, attaching a 10-foot-tall ladder, to which he had added self-made hooks, to the top of the wall. The driver then scrambled over, jumping into the West.

Local East German authorities described the incident as one in which “the border of East Germany was violently breached.” The incident prompted local officers to implement more stringent controls for people and vehicles passing into the restricted zones. Officials ordered the removal of all the trees blocking the view from the village border watchtower to the frontier, and the erection of an additional mesh metal fence in front of the wall.

East Germany continued building up its western border, and by 1981, Mödlareuth’s border regiment declared the technical militarization of its section of the border to be “fully completed.” Then-Vice President George H.W. Bush visited the western side of Mödlareuth in 1983, declaring in front of western villagers, “Ich bin ein Mödlareuther,” echoing John F. Kennedy’s famous 1963 address in West Berlin. Soon after, Bush described the wall through Mödlareuth as “an even greater obscenity than its eponym” in Berlin.

The 1973 escape was the only successful breach of the Mödlareuth wall. By and large, the wall worked extremely well. Though villagers worked to keep the community united, the wall profoundly disrupted village life. Family connections were shattered. One brother in eastern Mödlareuth was separated from his brother in the western half.

In short, the lesson of Mödlareuth is that walls work. They work even better these days, thanks to great leaps in technology since the Cold War. But countries fixated on building walls generally do not work. The rhetoric and actions surrounding the construction of walls often indicate major social problems. In East Germany, it was many citizens’ rejection of a restrictive, one-party regime that restricted opportunities and suppressed freedoms.

Even as Mikhail Gorbachev implemented reforms in the Soviet Union in the late 1980s, allowing Warsaw Pact states such as East Germany latitude in determining their national programs, the East German government refused to implement reforms. By autumn 1989, mass demonstrations against this intransigence began with protests in major East German cities. The wall in Berlin came down in November, the Mödlareuth wall was opened in December, and by the next year, East Germany was, as they say, history.

In the United States today, the Trump administration’s focus on wall-building along the southern frontier is again a marker of societal problems. It represents foolish isolationism, antiquated xenophobia and a rejection of the modern global community.

Rather than solving our problems by trying to keep immigrants (and foreign goods) out, President Trump should work with Congress to develop a humane immigration policy that prevents the separation of families and offers a real solution to beneficiaries of Deferred Action for Childhood Arrivals program. This policy should also recognize the vital role immigrants play in the U.S. economy. In my home state of Texas, for example, 1 in 6 residents are immigrants. Were those Texans to disappear overnight, the state would all but cease to function.

Should Trump and his Republican allies push forward with their border policy, the fate of the U.S.-Mexico wall may mimic the fate of the old East German wall in Mödlareuth: It might achieve its narrow objective, but it will also symbolize the perils of ossified thinking and the failure to embrace forward-looking reforms.