Events from the year 1938 in the United States.
- July 3 – The last reunion of the Blue and Gray commemorates the 75th anniversary of the Battle of Gettysburg in Gettysburg, Pennsylvania.
- July 5 – The Non-Intervention Committee reaches an agreement to withdraw all foreign volunteers from the Spanish Civil War. The agreement is respected by most Republican foreign volunteers, notably by those from England and the United States, but is ignored by the governments of Germany and Italy.
- July 18 – Wrong Way Corrigan takes off from New York, ostensibly heading for California. He lands in Ireland instead.
- August 6 – The Looney Tunes animated short Porky & Daffy is released.
- August 18 – The Thousand Islands Bridge, connecting the United States with Canada, is dedicated by U.S. President Franklin D. Roosevelt.
- August 31 – Winston Churchill, still believing France and Britain mean to honor their promises to defend Czechoslovakia against Nazi aggression, suggests in a personal note to Neville Chamberlain that His Majesty's Government may want to set up a broad international alliance including the United States (specifically mentioning U.S. President Franklin D. Roosevelt as possibly receptive to the idea) and the Soviet Union.
- September 4 – During the ceremony marking the unveiling of a plaque at Pointe de Grave, France celebrating Franco-American friendship, American Ambassador William Bullitt in a speech states, "France and the United States were united in war and peace", leading to much speculation in the press that if war did break out over Czechoslovakia, then the United States would join the war on the Allied side.
- September 9 – U.S. President Franklin D. Roosevelt disallows the popular interpretation of Bullitt’s speech at a press conference at the White House. Roosevelt states it is “100% wrong” the U.S. would join a “stop-Hitler bloc” under any circumstances, and makes it quite clear that in the event of German aggression against Czechoslovakia, the U.S. would remain neutral.
- September 12 – Hitler makes his much-anticipated closing address at Nuremberg, in which he vehemently attacks the Czech people and President Beneš. American news commentator Hans von Kaltenborn begins his famous marathon of broadcast bulletins over the CBS Radio Network with a summation of Hitler's address.
- September 21 – The New England Hurricane of 1938 strikes Long Island and southern New England, killing over 300 along the Rhode Island shoreline and approximately 600 in total.
- September 22 – Olsen and Johnson's musical comedy revue Hellzapoppin' begins its 3-year run on Broadway.
- October 10 – The Blue Water Bridge opens, connecting Port Huron, Michigan and Sarnia, Ontario.
- October 16 – Winston Churchill, in a broadcast address to the United States, condemns the Munich Agreement as a defeat and calls upon America and western Europe to prepare for armed resistance against Adolf Hitler.
- October 24 – The minimum wage is established by law in the United States.
- October 30 – Orson Welles's radio adaptation of The War of the Worlds is broadcast, causing panic in various parts of the United States.
- October 31 – Great Depression: In an effort to try restore investor confidence, the New York Stock Exchange unveils a 15-point program intended to upgrade protection for the investing public.
- November 1 – Horse Racing: Seabiscuit defeats War Admiral by four lengths in their famous match race at Pimlico Race Course in Baltimore, Maryland.
- November 10 – On the eve of Armistice Day, Kate Smith sings Irving Berlin's "God Bless America" for the first time on her weekly radio show.
- December – President Franklin Roosevelt agrees to lend $25 million to Chiang Kai-shek, cementing the Sino-American relationship and angering the Japanese government.
|This section requires expansion. (November 2011)|