72% of the dollar's purchasing power was destroyed in just four episodes

The US Consumer Price Index has tracked the cost of living since 1913, providing the longest continuous measure of inflation in the American economy. Over 113 years and 1,357 monthly observations, the CPI reveals a fundamental pattern that challenges the common perception of inflation as a slow, steady erosion: purchasing power destruction is not gradual. It arrives in concentrated bursts — episodic regime breaks separated by extended periods of relative stability.

The US dollar has lost 96.9% of its purchasing power since 1914 — but this destruction was not gradual. Four inflationary episodes (WWI, WWII and the post-war boom, the Great Inflation of 1968–1982, and the post-COVID surge of 2021–2023) account for 72% of the total cumulative price increase, despite spanning only 29% of the total time. Inflation is not a slow leak. It is a series of regime breaks.

Key Findings from the Dataset

• Purchasing Power Loss: The US dollar has lost 96.9% of its purchasing power since January 1914. The CPI index has risen from 10.0 to 327.5 — a 32.7× multiplier — according to BLS data (retrieved March 2026).
• Concentrated Destruction: This destruction was not gradual. Four concentrated inflationary episodes — WWI (1916–1920), WWII and the post-war boom (1941–1951), the Great Inflation (1968–1982), and the post-COVID surge (2021–2023) — account for 72% of the total cumulative price increase, despite spanning only 29% of the 113-year dataset.
• The Great Inflation: The Great Inflation of 1968–1982 alone accounts for 30.2% of all cumulative purchasing power destruction since 1914 — more than WWI and WWII combined. During this 15-year period, the CPI rose from 34.1 to 97.7, nearly tripling the price level.
• Deflation Trends: Deflation — negative year-over-year CPI change — has occurred in 13.0% of all months since 1914 but has been entirely absent since April 2015. The longest sustained deflationary period was the Great Depression (1930–1933), when prices fell by approximately 27%.
• Fed Targets: Of the 1,345 months with calculable year-over-year inflation, 61.6% exceeded the modern Federal Reserve’s 2% target. The median annual inflation rate across the full sample is 2.7%.

The Gradual Erosion Myth

The dominant popular narrative about inflation operates on a simple metaphor: inflation is a slow, steady drip that quietly erodes purchasing power over time. This metaphor is empirically wrong. The data tells a different story.

Of the 1,345 months analyzed, 57.4% recorded annual price changes between 0% and 4%. In these months, the purchasing power erosion was indeed gradual. If the entire 113-year period had proceeded at this pace, $100 in 1914 would still be worth approximately $12–20 today. Instead, $100 in 1914 is worth $3.05 today. The gap is explained almost entirely by four concentrated episodes where annual inflation exceeded 5% for sustained periods.

The Power of Compounding

Inflation compounds. A single year of 10% inflation destroys as much purchasing power as five years of 2% inflation. When 10% inflation persists for several consecutive years, the compounding effect is devastating. This is why 29% of the time produced 72% of the cumulative damage. Inflation is not a slow leak; it is a series of regime breaks, each driven by a distinct macroeconomic mechanism.