How do past Iowa polls compare to Iowa election results?

Voter preference surveys are not designed to predict victories. These are snapshots in time that help news outlets and the general public better understand what likely voters are thinking about and what issues are important to them right now.

But many are turning to polls taken close to the election to get a better idea of how Election Day might play out.

In Iowa, The Des Moines Register has been polling Iowans since 1943, when pollsters first fanned out across the state to survey Iowans right on their doorstep. Since 1987, J. Ann Selzer has led the Iowa poll, first as a Register employee and, since 1997, on a contract basis with her firm Selzer & Co.

When Iowa polling data is released, readers often wonder how close past polls are to the final election results. Here’s a look at polling in Iowa ahead of US presidential elections over the past 20 years.

2020: Final Iowa poll shows Donald Trump ahead of Joe Biden

The latest 2020 Des Moines Register/Mediacom poll was conducted October 26-29, 2020, just days before the November 3, 2020 election. The results showed then-President Donald Trump leading the state, 48% to Joe Biden’s 41%.

The 7-point lead was a departure from a September 2020 Iowa poll that showed the state’s race close.

This closely matched the final results, which saw Trump win Iowa by 8 points (53% to 45%).

2016: Final Iowa poll shows Donald Trump defeating Hillary Clinton

Since voting for President Barack Obama in Iowa’s back-to-back 2016 elections, there have been multiple campaigns by both Donald Trump and Hillary Clinton.

The final Des Moines Register/Mediacom Iowa poll showed Trump ahead of Clinton by 7 points (46% to 39%). The survey was conducted November 1–4, 2016, ahead of the November 8, 2016 elections.

It wasn’t until 1:30 the next day that the Associated Press called the race for Trump. Trump finished with a 9.4 point lead over Clinton (51.1% to 41.7%).

2012: According to the results of the final poll in Iowa, Barack Obama was ahead of Mitt Romney

President Barack Obama faced challenger Mitt Romney in 2012.

In the latest Des Moines Register/Mediacom Iowa poll, Obama led Romney by 5 points (47% to 42%).

On election night, Obama carried the state by 6 points (52% to 46%).

2008: Barack Obama has a commanding lead over John McCain in the final Iowa polls.

Iowa helped propel Barack Obama as a presidential candidate when he won the 2008 Iowa caucuses.

Ahead of Election Day, the final poll in Iowa looked like Obama would easily beat challenger John McCain. The poll showed him with a 17-point lead (54% to 37%).

When the polls closed, Obama had won the state by a narrower margin: 10 points. He received 54% of the vote, while McCain received 44%.

2004: John Kerry beats President George W. Bush.

In 2004, Iowa was seen as a battleground after President George W. Bush was dogged by low job approval ratings. Iowa did not vote for Bush in 2000, choosing former Vice President Al Gore instead.

The final Iowa poll showed U.S. Sen. John Kerry, the Democratic challenger, leading by 5 points (48% to 43%).

On election night, Bush narrowly won with 49.9% of the vote compared to Kerry’s 49.2%. Bush was the first Republican to win the state since Ronald Reagan in 1984.

Brian Smith is the Register’s audience growth strategist. Contact him at [email protected] or 515-284-8214.