The Long-Run Aggregate Supply (LRAS) curve is a vertical line at full-employment output, showing that in the long run an economy's production is set by its resources, technology, and capital, not the price level. A rightward shift of LRAS represents economic growth, the same idea as an outward shift of the PPC.
The LRAS curve shows how much an economy produces when every resource is being used efficiently and the economy is at full employment. It's drawn as a vertical line at potential output. Why vertical? Because in the long run, prices and wages have fully adjusted, so the price level can't change how much the economy is capable of producing. Capacity comes from real stuff, like the size of the labor force, physical and human capital per worker, and the level of technology.
Here's the intuitive version. LRAS is the economy's speed limit drawn on the AD-AS graph. Short-run output can swing above or below it (booms and recessions), but the only way to permanently raise output is to move the line itself. That's why a rightward shift of LRAS literally is economic growth, and why the CED says an outward shift of the PPC is analogous to a rightward shift of LRAS. They're two pictures of the same thing, an increase in productive capacity.
LRAS anchors Topic 5.6 (Economic Growth) in Unit 5, Long-Run Consequences of Stabilization Policies. Learning objective AP Macro 5.6.A has you define the determinants of growth (productivity, physical and human capital per worker, technology), and those determinants are exactly what shift LRAS. Learning objective AP Macro 5.6.B asks you to explain, with graphs, how the PPC relates to the LRAS curve. The big payoff is conceptual. Fiscal and monetary policy shift AD and move you around in the short run, but only changes in capacity move LRAS. That distinction between short-run stabilization and long-run growth is the whole point of Unit 5.
Production Possibilities Curve (Units 1 & 5)
The PPC from Unit 1 and the LRAS curve are the same idea in two different graphs. Both show maximum sustainable output, so anything that pushes the PPC outward (more capital, better technology) also shifts LRAS right. The CED makes this analogy explicit in 5.6.B.
Potential Output (Units 3 & 5)
LRAS is literally drawn at potential output, also called full-employment GDP. If actual output is left of LRAS, you have a recessionary gap; if it's right of LRAS, an inflationary gap. The LRAS line is the reference point for every output gap question in the AD-AS model.
Aggregate Production Function (Unit 5)
The aggregate production function explains why LRAS sits where it sits. Output per capita rises with physical capital, human capital, and technology, so anything that boosts those inputs raises potential output and shifts LRAS right.
Aggregate Demand (Unit 3)
AD shifts change output only in the short run. In the long run the economy self-corrects back to LRAS at a different price level. This is the cleanest way to see why expansionary policy can't permanently push output past potential.
LRAS shows up constantly in the AD-AS graphing FRQs. The 2021 FRQ Q1 starts with Sweden in long-run equilibrium, which means you draw AD, SRAS, and LRAS all intersecting at one point. The 2024 FRQ Q1 gives Alpha a 3% cyclical unemployment rate, so equilibrium output sits to the left of LRAS, and you have to draw that gap correctly. Recession setups like the 2018 and 2019 SAQs work the same way. Multiple-choice questions hit the PPC-LRAS analogy directly, asking what technological innovation does to both graphs (both shift outward/rightward) or where an economy with idle resources sits relative to LRAS (inside the PPC, left of LRAS). Two skills matter most. Draw LRAS as a vertical line and label it. Know that demand-side events move the economy along or away from LRAS, while only capacity changes move LRAS itself.
SRAS is upward-sloping because in the short run some prices (especially wages) are sticky, so a higher price level temporarily coaxes out more output. LRAS is vertical because in the long run all prices adjust, leaving real capacity unchanged. Quick test on the exam: supply shocks like oil prices or wage changes shift SRAS, while changes in resources, capital, or technology shift LRAS. A higher price level shifts neither, it's just a movement along SRAS.
The LRAS curve is vertical at full-employment (potential) output because in the long run the price level does not affect how much an economy can produce.
A rightward shift of LRAS represents economic growth, and it's analogous to an outward shift of the PPC (CED 5.6.B).
LRAS shifts when the determinants of capacity change, meaning technology, physical capital, human capital, or the size of the labor force.
Changes in aggregate demand or the price level do NOT shift LRAS; they create short-run gaps that the economy eventually self-corrects back to LRAS.
On AD-AS graphing FRQs, a recessionary gap means equilibrium output is left of LRAS, and an inflationary gap means it's right of LRAS.
Economic growth is measured as growth in real GDP per capita over time, and on the graph it shows up as LRAS moving right.
The Long-Run Aggregate Supply curve is a vertical line at full-employment output. It shows that an economy's long-run production is determined by its resources, capital, and technology, not by the price level.
Because in the long run, all prices and wages have fully adjusted. A higher price level can't squeeze out more output when the economy is already using its resources efficiently, so capacity is fixed at potential output regardless of prices.
No. AD shifts change output only in the short run and change the price level in the long run, but LRAS stays put. Only changes in productive capacity, like new technology or more physical and human capital, shift LRAS.
SRAS slopes upward because wages and some prices are sticky in the short run, so output responds to the price level. LRAS is vertical because everything has adjusted. Supply shocks shift SRAS, while capacity changes shift LRAS.
They show the same concept, maximum sustainable output, in different models. The CED states that an outward shift in the PPC is analogous to a rightward shift of LRAS, so technological innovation moves both the same direction.