He studied at the University of Wisconsin, Madison, and later obtained his PhD in physics at Harvard University in 1939. During this time he encountered differential equations that he could only solve numerically. As such, he envisioned an electro-mechanical computing device that could do much of the tedious work for him. This computer was originally called the Automatic Sequence Controlled Calculator (ASCC) and later renamed Harvard Mark I. With help from Grace Hopper and funding from IBM the machine was completed in 1944. In 1947, Aiken completed his work on the fully electronic Mark II computer.
He is also well known for his 1947 comment, "Only six electronic digital computers would be required to satisfy the computing needs of the entire United States."