The project started humbly. In the pre-drone era about a decade after the end of World War II, President Eisenhower signed off on a project aimed at building a high-altitude, long-range, manned aircraft that could photograph remote targets. Working together, the Air Force and Lockheed developed a craft that could hold the high-resolution cameras required for the images, a craft that became the U-2. Why "U-2"?
They decided that they could not call the project aircraft a bomber, fighter, or transport plane, and they did not want anyone to know that the new plane was for reconnaissance, so [Air Force officers] Geary and Culbertson decided that it should come under the utility aircraft category. At the time, there were only two utility aircraft on the books, a U-1 and a U-3. told Culbertson that the Lockheed CL-282 was going to be known officially as the U-2.