Event of Interest
Apr 1 Filipino President Quezon officially authorizes the printing and publication of the grammar and dictionary prepared by the Institute of the National Language.

Manuel L. Quezon
Music Premiere
Apr 4 Richard Rodgers and Lorenz Hart's musical "Higher & Higher" premieres in NYC

Richard Rodgers
- Apr 5 99th Grand National: 25/1 shot Bogskar ridden by Royal Air Force sergeant Mervyn Jones wins by 4 lengths from MacMoffat; last true Aintree GN before a 5-year break due to World War II
- Apr 7 7th US Masters Tournament, Augusta National GC: Jimmy Demaret wins the first of his 3 Masters titles, 4 strokes ahead of runner-up Lloyd Mangrum
Event of Interest
Apr 7 US Post Office issues first postage stamp of African American educator Booker T. Washington

Booker T. Washington
Event of Interest
Apr 10 Vidkun Quisling forms Norwegian "national government"

Vidkun Quisling
- Apr 12 Italy annexes Albania
- Apr 12 NFL cuts clipping penalty from 25 yards to 15 yards
- Apr 13 Second battle of Narvik; 3 German destroyers and one U-boat sunk by the Royal Navy, 5 more German destroyers scuttled.
- Apr 13 Cornelious Warmerdam became 1st man to pole vault 15 ft
- Apr 13 Stanley Cup Final, Maple Leaf Gardens, Toronto, ON: New York Rangers beat Toronto Maple Leafs, 3-2 for 4-2 series victory; Rangers last Cup win for 54 years
- Apr 14 Allied troops land in Norway
- Apr 14 RCA demonstrated its new electron microscope in Philadelphia
- Apr 15 British troops land at Narvik, Norway
- Apr 15 44th Boston Marathon won by Gérard Côté of Canada in 2:28:28.6; first of 4 wins in the event
- Apr 16 Cleveland Indian Bob Feller hurls an opening day no-hitter vs Chic, 1-0
- Apr 16 Heitor Villa-Lobos' opera "Izaht" premieres in Rio de Janeiro
- Apr 19 "Lake Shore Ltd" derails speed killing 34 near Little Falls, New York
- Apr 19 Dutch prime minister De Geer declares state of siege
- Apr 20 1st electron microscope demonstrated (RCA), Philadelphia, Pa
- Apr 21 1st $64 Question, "Take It or Leave It," on CBS Radio
- Apr 22 Rear Admiral Joseph Taussig testifies before US Senate Naval Affairs Committee that war with Japan is inevitable
- Apr 23 Dance hall fires kills 198 in Natchez, Mississippi
- Apr 23 NY Yankees dedicate a plaque to Jacob Rupert

Heinrich Himmler
Music Recording
Apr 28 Glenn Miller records "Pennsylvania 6-5000"

Glenn Miller
- Apr 28 SS-Obersturmbannführer (lieutenant colonel) Rudolf Höss (not Hess, different Nazi) becomes commandant of concentration camp Auschwitz
- Apr 29 1st radio broadcast of "Young Dr Malone" on CBS
- Apr 29 Norwegian King Haakon & government flee to Britain
- Apr 29 Robert Sherwood's play "There Shall be No Night" premieres in NYC
- Apr 30 Air New Zealand then known as TEAL makes its inaugural flight with a flight from Auckland to Sydney. Later becomes 1st airline in the world to boil hot water in-flight to offer customers hot tea and coffee.
- Apr 30 Brooklyn Dodger Tex Carleton no-hits Cincinnati Reds, 3-0