A new election cycle will bring a surge in political polling — and not all polls will be reliable. Some of the biggest misses in recent elections highlight flaws in traditional polling methods.

The original sin of American polling came in 1936, when Literary Digest surveyed its readership and declared that Alf Landon would likely be the next president. Landon lost, and a year later, the ...

President Donald Trump wants to end mail-in voting, forcing Americans to go to the polls in person to cast their ballots. It’s a move polling shows a majority of the public opposes. Data from past ...