Maria's River becomes the Marias
"The glory and the nothing of a name"
In the mid-1850s the apostrophe was still there. It was still Lewis's cousin's river—"Muh-ree-uz" River. Or maybe she would have preferred "muh-rye-uz." Ten years later the apostrophe was gone, which permitted the s to shed its genitive-case buzz. Finally, a definite article crept in to particularize this river as its very own river, and nobody else's. The Marias—Muh-rye-us—it was, and is, and evermore shall be.
It would have happened eventually anyhow. The moniker-minding U.S. Geological Survey drops apostrophes from all official place names.
On Saturday, June 8, 1805, with five days of exploration and study behind him, Meriwether Lewis stamped his considered opinion with a grand gesture—perhaps with a twinge of homesickness. Only a week earlier, Clark had affectionately named a river after young Julia (Judith) Hancock, whom he was to marry in 1808. Now it was Lewis's turn. He had no way of knowing that Blackfeet Indians had already named it Bear River.
The whole of my party to a man except myself were fully perswaided that this river was the Missouri, but being fully of opinion that it was neither the main stream or that which it would be advisable for us to take, I determined to give it a name and in honour of Miss Maria W____d. [Wood] called it Maria's River.
With apologies to his cousin Maria, Lewis continued:
It is true that the hue of the waters of this turbulent and troubled stream but illy comport with the pure celestial virtues and amiable qualifications of that lovely fair one; but on the other hand it is a noble river....
Now he began to sound less like an admiring relative and more like a local booster, growing more resonant with each breath.
…one destined to become in my opinion an object of contention between the two great powers of America and Great Britin with rispect to the adjustment of the North westwardly boundary of the former; and that it will become one of the most interesting brances of the Missouri in a commercial point of view, I have but little doubt, as it abounds with anamals of the fur kind, and most probably furnishes a safe and direct communication to that productive country of valuable furs exclusively enjoyed at present by the subjects of his Britanic Majesty…
That took care of the geopolitics of his cousin's river, including the Anglophobia that was behind his own impulse to explore it further, at another time. Now, back to the enthralling beauty of its setting, with no apology for allowing his passion to mislead his judgment.
…in adition to which it passes through a rich fertile and one of the most beatifully picteresque countries that I ever beheld, through the wide expance of which, innumerable herds of living anamals are seen, it's borders garnished with one continued garden of roses, while it's lofty and open forests, are the habitation of miriads of the feathered tribes who salute the ear of the passing traveler with their wild and simple, yet s[w]eet and cheerful melody.
Well, he was right about the roses and the birds, anyhow.