The Pledge of Allegiance received official recognition by Congress in an Act approved on June 22, 1942. However, the pledge was first published in 1892 in the Youth's Companion magazine in Boston, Massachusetts to celebrate the 400th anniversary of the discovery of America, and was first used in public schools to celebrate Columbus Day on October 12, 1892.

In its original version, the pledge read "my flag" instead of "the flag of the United States." The change in the wording was adopted by the National Flag Conference in 1923. The rationale for the change was that it prevented ambiguity among foreign-born children and adults who might have the flag of their native land in mind when reciting the pledge.

The phrase "under God" was added to the pledge by a Congressional act approved on June 14, 1954. At that time, President Eisenhower said:

"in this way we are reaffirming the transcendence of religious faith in America's heritage and future; in this way we shall constantly strengthen those spiritual weapons which forever will be our country's most powerful resource in peace and war."