Really, if you're going to make assertations, you should do your own research and not depend on me to suppy it.
Nevertheless, according to David Lawson (the first of several Paul Morphy games published overseas prior to the American Chess Congress):
The following game with Rousseau is the first Paul Morphy game to be published and it has become a part of chess history, Ernest Morphy sent it to Kieseritzky, together with a letter, and both were published in the January issue of La Régence as follows:
New Orleans October 31, 1849
Dear sir,
I send you herewith a game of chess played on the 28th instant between Mr. R. [Rousseau] and the young Paul Morphy, my nephew, who is only twelve. This child has never opened a work of chess; he has learnt the game himself by following the parties played between members of his family. In the openings he makes the right moves as if by inspiration; and it is astonishing to note the precision of his calculations in the middle and end game. When seated before a chessboard, his face betrays no agitation even in the most critical positions; in such cases he generally whistles an air through his teeth and patiently seeks for the combination to get him out of trouble. Further, he plays three or four severe enough games every Sunday (the only day on which his father allows him to play) without showing the least fatigue.
Your devoted friend
Ernest Morphy
La Régence was published in France. France, as you may know, is across the ocean and Paul was 12.
"Perhaps a few old men in the New Orleans chess club were aware of him and thats about it." apparently includes Eugene Rousseau who a few year prior was vying for the first US championship, and who was able to win only 5 out of 50 games against 11 year old Morphy between 1848-9 (one of the later losses was the above game).
As for the spread of fame after defeating Lowenthal, Lawson claimed:
"Henceforth his reputation extended beyond the circle of relatives and friends, and if, prior to this encounter, there had been doubtful Thomases who had misgivings about his genius, they certainly disappeared now.
Such, indeed, was the confidence inspired by his victory over Löwenthal that certain gentlemen, with more enthusiasm than discretion, suggested to Judge Morphy the propriety his son to the International Chess Congress announced to take place in London in 1851."
That particular encounter wasn't heralded right away, but still, prior to the Congress, indicating (along with the invitation itself) Morphy was a well-known quantity: Lawson again: "In 1856 and 1857 the game appeared in the five following publications: in the Unites States, England, and Switzerland as it had been presented by Ernest Morphy in the New York Clipper, Staunton’s Illustrated London News, Frank Leslie’s Illustrated Newspaper, Porter’s Spirit of the Times and the Schweizerische Schachzeitung."
After Morphy turned down the invitation to play in the first congress, Fiske wrote to Charles de Maurian the following letter, the contents of which plainly and clearly reveal Morphy's status in the American, and international, chess world:
Charles A. Maurian, New Orleans
Dear Sir:-- Mr. Michard sailed for New Orleans yesterday and will bring you the latest news in reference to the Great Congress…
The great question here, as well as throughout the entire North, is will Paul Morphy come? In spite of the adverse belief of Mr. Michinard, we all hope that he will. The bare announcement that he might be certainly expected would help on our subscription in this part of the Union more than all other circumstances combined. Assure him that whether victor or loser, he would be the lion of the tournament, double the interest of the tournament and add largely to its respectability abroad.
Let me beg you to state all these things to Mr. Morphy, and convince him that no other person has it in his power to do so much good to American Chess as he has, and that the entire community of chess players confidently expect it at his hands.
Mr Hammond of Boston; Montgomery, Thomas, Elkin, Baldwin and Doughtery of Philadelphia; Montgomery of Georgia; Cheney of Syracuse; Calthrop of Connecticut, besides Stanley and others, of New York, will play in the tournament. We were all much pleased with Mr. Michard’s vistit. I only regret that I came in too late from the country to see much of him.
Yours
Daniel W. Fiske
You might also want to study the history of New Orleans. According to Thomas F. McIlwraith, Edward K. Muller in North America: the historical geography of a changing continent: "The Crescent City had risen by 1840 to 102,000 [population] and fifth among all American cities; it was almost precisely the size of Baltimore." (Compared to other American cities in 1840 - Cincinatti with 46,000, Pittsburgh with 31,0000, Louisville with 21,000, St. Louis with 16,500, Buffalo with 18,000 - twice the size of Detroit, Chicago with 30,000.)
Retrospective ranking is an interesting and attractive invention but the raw math it is enought to compare players of different times. There is no a scientistific tool to compare the strenght of play various great players. Who was better Morphy ,Capablanca , Fischer, Anand? Ranking doesn't answer the question.
I know Players like Capa or Morphy in their time adapted to their opponents. Morphy today would play differently .