Donald Trump's at it again with the name changes ... and this time, he's got his eyes on one of our states.

The Prez took to Truth Social Monday to insist New Mexico change its name to New America, arguing ... "We are not Mexico, we are the United States of America!"

Trump even seems to believe the new moniker would boost the state's economy, saying ... "The name would add great value and prestige to the State! Home Values and Incomes would rise, and you would be even prouder while saluting our beautiful American Flag!"

Seems voting results may be behind Trump's latest idea ... he ends his rant, "Maybe even the Crooked Elections, that New Mexico is known for, would become honest again!"

It's just the latest in Trump's absurd attempts to change names of various landmarks -- including the Gulf of Mexico and Lake Ontario. He signed executive orders to change those to Gulf of America and Lake America.

No word if Trump's planning to rename New England.