Trump's victory was confirmed shortly before 10 a.m. Latvian time.
Given his comments during his campaign about not necessarily protecting fellow NATO member states from Russian aggression if he became president, his victory would be of some concern to Latvia, to put it mildly.
He has also repeatedly praised Russian president Vladimir Putin and his campaign has been linked in various ways with Russian support.
The US Embassy published a video clip of Ambassador Nancy Bikoff Pettit saying the US would continue to be a strong partner to Latvia, before the result had even been announced.
"Latvia is a wonderful partner to the United States. That will not change no matter what the outcome of this election. What we're seeing today is democracy in action," the ambassador told LTV shortly afterwards.
"I am absolutely, 100% certain that we will have a continuation of a strong and very close US-Latvia relationship. We will continue to focus on our security and defense relationship and on broadening and deepening our economic ties to Latvia," she said.
However, as she also acknowledged when speaking to LTV, she is a Presidential appointee and the new President will have the right to appoint whoever he wishes.
Her deputy, Sharon Hudson-Dean told the Riga 24 news channel: "We fully intend to maintain this strong relationship - the NATO treaty is US law."
Quite how Trump will act with regard to foreign policy once he has access to the world's most powerful military and the nuclear codes can only be guessed at.