Chart assignment

Charts to read and discuss

Read each chart, then answer its questions. Every chart shows its source and date; open it for a table of the numbers and the data to download.

  1. How much of US electricity comes from coal?
  2. How big is the federal debt compared with the economy?

Chart 1 of 2 · Energy

How much of US electricity comes from coal?

The interactive chart needs JavaScript. The numbers are on the chart's page.

Coal made 16.6% of US electricity in 2025, down from a peak of 56.9% in 1988 and 48.5% as late as 2007. Natural gas overtook it in 2016. Each point is coal's share of all net generation that year; the 2025 figures are preliminary.

Questions to discuss

  1. In one sentence of your own, what does this chart show?
  2. Find the biggest change or difference in the chart. What might explain it?
  3. Who collected these numbers, and how recent are they? What else would you want to know before drawing a conclusion?

Source: U.S. Energy Information Administration, Monthly Energy Review (Table 7.2a) (Public domain (U.S. government work)) · Data as of Dec 31, 2025

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Chart 2 of 2 · Federal budget

How big is the federal debt compared with the economy?

The interactive chart needs JavaScript. The numbers are on the chart's page.

At the end of fiscal 2026 the federal debt was 125% of a year's GDP, everything the U.S. economy produces in a year. It fell from 96% in 1948 to a low of 32% in 1981, passed 100% in 2013 and jumped to 126% in 2020. This is total debt, including what the government owes its own trust funds, divided by GDP over the same fiscal year; it starts in 1948 because BEA's quarterly GDP starts in 1947, and recent GDP figures are revised.

How to read this chart

Each point divides the federal government's total debt by GDP, everything the U.S. economy produces in a year. At 100%, the debt equals one year of the whole economy's output. Comparing debt with the economy's size, instead of in dollars, makes years decades apart fair to compare.

Questions to discuss

  1. When was the debt smallest compared with the economy, and when was it largest?
  2. The debt can grow in dollars while this percentage falls. How is that possible?
  3. Pick a big jump on the chart. What events could make the government borrow much more in a short time?

Source: U.S. Treasury Fiscal Data, Historical Debt Outstanding; GDP from the Bureau of Economic Analysis (NIPA Table 1.1.5) (Public domain (U.S. government work)) · Data as of Sep 30, 2026

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