Stagflation Explained: When Inflation and Unemployment Rise Together

Stagflation is the simultaneous combination of stagnant growth, high unemployment, and high inflation. It is the one macroeconomic situation that ordinary demand-side policy cannot fix, because any tool that cures one half of the problem makes the other half worse. Cut interest rates to fight unemployment and you fuel more inflation. Raise rates to fight inflation and you deepen the recession. The word itself is a blend of stagnation and inflation, and understanding why it happens is one of the clearest tests of whether you really understand the Phillips curve.

This guide explains what stagflation is, why the economics of the 1960s said it should be nearly impossible, what actually broke in the 1970s, and how the graphs show the trap. It is written to line up with what the AP Macroeconomics exam expects.

What Is Stagflation?

Normally, inflation and unemployment move in opposite directions. When the economy is booming, unemployment is low and prices are rising quickly. When the economy is in a slump, unemployment is high and inflation is low or even negative. That inverse relationship is the whole idea behind the short-run Phillips curve, which slopes downward: less unemployment tends to come bundled with more inflation.

Stagflation breaks that pattern. Both numbers are high at the same time. Output stagnates, joblessness climbs, and yet the cost of living keeps rising fast. It is the worst of both worlds, and it is exactly the outcome the standard 1960s models treated as an anomaly. You can see the relationship the model is built on in the unemployment and inflation module, and you can push the curves around yourself in the Phillips curve sandbox.

Why the 1960s Said It Should Not Happen

In 1958 the economist A.W. Phillips studied nearly a century of British data and found a stable inverse relationship between wage growth and unemployment. Through the 1960s, policymakers came to read that relationship as a fixed menu of choices: pick the unemployment rate you want, accept the inflation rate that comes with it, and buy lower joblessness by tolerating a bit more inflation.

That view assumed the tradeoff was permanent. If it were, stagflation could not occur, because high unemployment would always sit at the low-inflation end of the curve. You simply could not be at high unemployment and high inflation at the same time, since those are opposite corners of a single downward-sloping line.

Two economists challenged this. Milton Friedman and Edmund Phelps argued, around 1968, that the tradeoff was only short run. Once workers and firms come to expect a given inflation rate, they build it into wage demands and price setting, and the whole short-run Phillips curve shifts up. In the long run, they said, the economy always returns to its natural rate of unemployment regardless of inflation, so the long-run Phillips curve is a vertical line. Their prediction was sharp: any attempt to hold unemployment below the natural rate for long would not buy a stable lower unemployment rate, it would buy accelerating inflation. Within a few years, events proved them right.

What Broke in the 1970s

The 1970s delivered the textbook case of stagflation, and it arrived through the supply side, not the demand side.

In October 1973, OPEC imposed an oil embargo and the price of crude roughly quadrupled over the following months. Oil is an input to almost everything: transport, plastics, fertilizer, manufacturing, heating. When its price explodes, production costs rise across the entire economy at once. A second shock followed in 1979 after the Iranian Revolution disrupted supply again.

This is a negative supply shock. It is fundamentally different from a demand change. A fall in aggregate demand lowers output and lowers prices together. A supply shock lowers output while raising prices together. That second combination is stagflation.

The numbers from the period tell the story plainly. U.S. inflation, which had run around 1 to 3 percent in the mid-1960s, climbed into the double digits and peaked near 13 to 14 percent in 1980. Unemployment, instead of falling as the old Phillips menu promised, rose at the same time, reaching roughly 9 percent in the 1975 recession. When economists plotted inflation against unemployment for the 1970s, the tidy downward-sloping curve of the 1960s was gone. The points drifted up and out, exactly as an economy jumping onto higher and higher short-run Phillips curves would look. The expectations-augmented model had predicted this; the fixed-menu model could not explain it.

The Supply-Shock Mechanism on the Graphs

Stagflation is easiest to see across two linked diagrams, which is exactly how the AP exam likes to ask about it.

Start with the AD-AS model. A negative supply shock shifts short-run aggregate supply (SRAS) to the left. Read off the new intersection: the price level is higher (inflation) and real GDP is lower (a recession with rising unemployment). Nothing shifted aggregate demand; the damage came entirely from the cost side. You can review the supply side in the aggregate supply module.

Now translate that to the Phillips curve. Because a supply shock changes both variables in the bad direction, it does not move you along the existing short-run Phillips curve. It shifts the entire short-run Phillips curve up and to the right. At every level of unemployment, inflation is now higher. The economy ends up at a point with both more inflation and more unemployment than before, which is impossible if you stay on one downward-sloping curve. That shift is the graphical signature of stagflation, and it is the single most important thing to be able to draw. Practice moving it in the Phillips curve sandbox.

Why Policymakers Get Trapped

Here is the reason stagflation is so feared. Demand-side policy, whether fiscal or monetary, moves aggregate demand, and moving aggregate demand can only ever fix one of the two problems.

Suppose the central bank fights the unemployment half. It cuts interest rates, aggregate demand rises, output recovers and unemployment falls. But higher demand on top of already-high prices pushes inflation up further. You traded a worse inflation problem for a better unemployment number.

Now suppose it fights the inflation half instead. It raises interest rates, aggregate demand falls, and inflation cools. But lower demand deepens the downturn, so unemployment climbs even higher. You traded a worse recession for lower inflation.

There is no demand-side setting that improves both at once, because the root cause is a leftward shift of supply, not a movement of demand. This is why the standard advice for a supply shock is uncomfortable: to truly fix stagflation you need the supply curve to shift back out, through lower input costs, higher productivity, or a painful adjustment of inflation expectations.

How the 1970s Episode Finally Ended

The resolution is as instructive as the cause. By 1979, inflation expectations were entrenched: everyone expected high inflation, so everyone built it into wages and prices, which kept it high. Paul Volcker, appointed chair of the Federal Reserve in 1979, decided to break those expectations directly.

The Fed raised the federal funds rate to around 19 to 20 percent by 1981. This was deliberately, savagely contractionary. It caused the deep 1981 to 1982 recession, in which unemployment rose to about 10.8 percent, the highest since the Great Depression. But it worked on the one thing demand policy can affect in this situation: it convinced households and firms that the Fed would tolerate a recession rather than let inflation continue, so expected inflation collapsed. As expectations fell, the short-run Phillips curve shifted back down, and inflation dropped to around 3 to 4 percent by 1983.

The lesson the profession drew is the backbone of modern central banking: because expectations sit inside the Phillips curve, a credible commitment to low inflation is itself a policy tool. That idea runs directly into how monetary policy is conducted today.

Stagflation on the AP Exam

A few things the exam rewards:

Identify the cause as supply-side. If a prompt gives you rising oil prices, a bad harvest, a new tax on production, or a wage-push spiral, it is signaling a negative supply shock, and stagflation is the likely answer. Demand shifts do not produce stagflation.

Show it on both graphs consistently. SRAS shifts left in AD-AS (higher price level, lower real GDP), and the short-run Phillips curve shifts up and right. Make sure the two diagrams tell the same story.

Explain the policy dilemma. State clearly that expansionary policy would worsen inflation and contractionary policy would worsen unemployment, so demand-side tools cannot fix both. That sentence is often worth a rubric point.

Connect it to expectations. The reason the 1970s tradeoff kept getting worse, and the reason the Volcker disinflation was so costly, is that inflation expectations shift the short-run Phillips curve. If you want the deeper mechanics of how prices start rising in the first place, see what causes inflation.

Stagflation is not just a piece of history. It is the cleanest proof that the short-run Phillips curve is not a fixed menu, that supply shocks and expectations can shift it, and that no single demand-side lever can cure an economy that is stagnant and inflating at the same time. Draw the leftward SRAS shift, draw the upward Phillips curve shift, explain the trap, and you have the whole concept.