A 1940 wartime voting advocacy ad, put out by the Penn Mutual Insurance Company. 1940 was before optical tally systems, so you have to give the 'X' some allegorical license (don't mark your ballot like that!!), but the ad copy resonates well, 86 years on.

Here's a 1924 ad from Met Life Insurance, The text certainly sounds more anachronistic than the 1940 ad, but the message of encouraging voter turnout remains.

The following was an early 1980s ad by an organization called Ground Zero (wikipedia). While they were not primarily a voting advocacy group, they did dabble in it. Their primary mission was to raise awareness about nuclear weapon risk. It was started by a White House Security Council guy who was involved in the SALT talks in the 70s and 80s.

Related -> ad for the Suffragist, and related info (lemmy thread), and reminder that within living memory of the oldest among us, half our population didn't have a right to vote.

Edited because I cannot proofread