Why did the literary digest misjudge the 1936 election?

The major reason for the misjudgement is method of polling they used. The literary digest based their polls using their readers as the population.

One problem with this, is the polls are done during the great depression, so their readers are only the people within upper economic class who could afford the magazine during that period while overlooking the lower economic class.

The Literary Digest neglected to do as such in the race of 1936. The fundamental reason was the technique for surveying they utilized. The surveyed their perusers, who were well sufficiently off to in any case have the capacity to stand to purchase the magazine amid the despondency. They additionally surveyed vehicle and phone client, who around then would have been rich. Subsequently, they didn't take advantage of the beat of America.