The two most recent national polls of the presidential race showed unusually high levels of support for Libertarian candidate Gary Johnson. In the NBC/Wall Street Journal survey conducted between June 19 and 23, presumptive Democratic nominee Hillary Clinton was backed by 39 percent of respondents, to 38 percent for presumptive Republican nominee Donald Trump, 10 percent for Johnson and 6 percent for Green Party candidate Jill Stein. An ABC/Washington Post poll in the field between June 20 and 23 found 47 percent of respondents for Clinton, 37 percent for Trump, 7 percent for Johnson, and 3 percent for Stein.

Even taking into account the reality that support for third-party candidates “usually diminishes over the course of the [U.S. presidential] campaign,” and third-party candidates have often received less than half as much support on election day as they did in nationwide surveys from June, Johnson has potential to shatter previous records for Libertarians. A former Republican governor of New Mexico, Johnson received 1,275,821 popular votes as the Libertarian presidential nominee in 2012, just under 1 percent of the nationwide vote. The best showing for a Libertarian ticket in terms of vote share was 1.06 percent (921,128 votes) in 1980 for Ed Clark and his running mate David Koch, better known as one half of the Koch brothers.

I haven’t seen any Iowa polls yet that gave respondents the option of choosing Stein or Johnson as alternatives to Clinton and Trump, but now seems like a good time to examine Libertarian presidential performance in Iowa over the last four decades and Johnson’s chances to improve on his 2012 results.