The seventh group of the Famous Americans Issue honors five American inventors — Eli Whitney, Samuel F. B. Morse, Cyrus Hall McCormick, Elias Howe, and Alexander Graham Bell. A stylized drawing of a cog wheel, uplifted wings, and a lightning bolt symbolize the group. Designers at the Bureau of Engraving and Printing used these to represent power, light, and electricity. More recently, some have claimed that the bolt represents the "I have an idea!" moment shared by all these inventors.
The Post Office Department issued the Inventors group between October 7 and October 28, 1940, completing the thirty-five stamps set nine months after it had issued the first stamp. Almost all of these stamps were issued in the birthplace of the honoree, which stirred emotions and pride and gave many small towns a reason to celebrate.