Thanks for the help guys.
The first digital computer was Harvard’s Mark I.
Not viewed from this side of the Atlantic. The British Colossus was earlier, but you won't be told that in an American school. (anyone remember the U-571 movie?)
British Colossus - electronic, first run December 1943
American Mark I - electro-mechanical, first run May 1944
The IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I by Harvard University, was probably the last electro-mechanical computer. The British Colossus computers, used for decoding German encrypted messages, were the world's first programmable, digital, electronic, computing devices. They used vacuum tubes (thermionic valves) to perform the calculations and thus were not only earlier, but more modern than the Mark I. They were kept secret for many decades which led to claims of "firsts" in computing that later turned out to be incorrect.
In fact if you allow electro-mechanical calculating machines like the Mark I to be called "computers", then I think that the German Konrad Zuse's Mark 3 of 1941 has a prior claim.