Making mistakes is part of life. Serious people own up to them and correct themselves. Unfortunately, when it comes to NAFTA, this is not the practice of the Washington Post.

Ten years ago today, December 7, 2007, a Washington Post editorial attacked the three leading contenders for the Democratic nomination over their pledge to renegotiate NAFTA. The Post had long been a strong supporter of NAFTA, biasing both its news coverage and opinion pages to push pro-NAFTA views. Its editorial page staff was obviously upset to see Senators Hillary Clinton, John Edwards, and Barack Obama attack their beloved trade agreement.

The editorial, ironically titled “Trade Distortions,” told readers how NAFTA had provided large benefits to the United States. Then it stated:

“Not that any of the Democratic candidates seem to care, but the impact of NAFTA seems to have been both larger and more positive in Mexico than in the United States. Mexico's gross domestic product, now more than $875 billion, has more than quadrupled since 1987.”

This one was a headscratcher for two reasons. First, NAFTA took effect in 1994 — why was the Post telling us about Mexico’s growth since 1987?

But this was the less important gaffe in this sentence. Mexico’s GDP “has more than quadrupled?” That is a pretty incredible claim on its face. If GDP quadruples in two decades, it implies an annual growth rate of 7.2 percent. While many developing countries have a brief spurt where they grow at this pace for two or three years, sustaining this sort of growth for two decades is truly extraordinary. China managed to do it, but not many other countries have. Was there another China growth miracle hiding south of the border that had somehow had gone unnoticed?

It turns out there wasn’t. According to the International Monetary Fund, adjusting for inflation, Mexico’s GDP went from 6,564 billion pesos in 1987 to 12,088 billion pesos in 2007.[1] That translates into cumulative growth of 84.2 percent, quite a bit different from the “more than quadrupled” claimed by the Washington Post. Rather than being a near-record-setting growth pace, this translates into a thoroughly mediocre 3.1 percent annual rate of growth.

On a per capita basis, Mexico’s growth trailed growth in the United States, averaging just 1.5 percent annually, compared to 1.9 percent in the United States. That’s not the expected story. Poor countries are supposed to be catching up to rich countries.

So how did the Post get this one so badly wrong? It’s possible that it looked at Mexico’s nominal GDP growth. This measure doesn’t adjust for the effects of inflation. Since Mexico had a very serious problem with inflation over most of this period, its nominal GDP did more than quadruple.

In fact, Mexico’s nominal GDP increased by more than a factor of 50, from 217.6 billion pesos in 1987 to 11,403.3 billion pesos in 2007. That certainly qualifies as “more than quadrupled.”

However, runaway inflation hardly makes a good case for NAFTA. While concerns over inflation have arguably been excessive in recent decades, inflation running well into the double digits is certainly a problem. In any case, higher inflation is hardly an outcome worth boasting about.

Anyhow, whatever the cause of the original error, the really disturbing part of the story is the Post’s refusal to correct it even after I called it to their attention. People view a newspaper like the Post as authoritative. As long as the mistaken numbers on Mexico’s growth appear on the paper’s website, it is possible that readers will find the piece and assume the numbers are correct. This is why serious newspapers append a correction to the bottom of an article or column that includes a major error.

For some reason, the Post has chosen not to acknowledge and correct its error over the last ten years. Let’s hope we don’t have to write a second edition of this piece in 2027.

[1] This uses 2008 constant pesos.