Mexico celebrated third-quarter economic growth of 1.34% last week, putting its annual growth pace at 5.5%. But on a visit to The Wall Street Journal earlier this month, Mexican presidential candidate Enrique Peña Nieto stressed that the country's annual average growth rate over the past 10 years has been an anemic 1.7%. It has been, the Institutional Revolutionary Party (PRI) candidate said, the slowest 10-year period of growth in the past 70 years.

For steady long-term growth, Mr. Peña Nieto argued, Mexico needs to return...