Sonas ratingcalculations on chessmetrics.com are highly debateble. The calculations might be believeble from a purely statistical viewpoint, but the foundation for the calculations are very weak, since we in fact know very few results prior to London 1851.

So there is very little facts - if any - to substansuate a claim, that Schulten would have been the second best rated in the world by januar 1851.

<Cable advices announce the sudden death of Mr. John W. Schulten, which occurred the 25th inst., in the City of Berlin, where he had lived for many years in charge of the business of Messrs. A. T. Stewart & Co. for all Germany. Mr. Schulten was some years ago a well-known merchant of this City, and will be well remembered for his kind and social qualities by those who enjoyed his personal acquaintance.>

Gaige claims Schulten was born in Germany, but has no year of birth, so where does the 1821 at Wikipedia come from, I wonder. That he was already playing serious matches with Rousseau in 1841 and with Stanley in 1844/45 - when, in 1845, he's described as the president of the New York CC - suggest that he must be older.

Did he come to America as a child? Or to set up in business?

<Between 1846 and 1848, the construction and finishing details of one of Stewart's most famous buildings, the "Marble Palace" at 280 Broadway, were completed. This establishment, "the cradle of the department store",[8] sent A. T. Stewart & Company to the top of America's most successful retailers.>

<The subscribers hereby give notice that they have formed a limited Partnership pursuant to the laws of the state of New York concerning Limited Partnerships. The name or firm under which said partnership is to be conducted is J. W. SCHULTEN & HURD. The general nature of the business intended to be transacted by the said partnership is a general mercantile and commission buiness. The general partners interested in the said partnership are John W. Schulten and Chauncey D. Hurd, both residing in the city of New York. The special partner is Pierre Antoine Jules Blanc, residing at Faverges, in the duchy of Savoy, kingdom of Sardinia. The said special partner has contributed to the common stock of the said copartnership the sum of one hundred thousand dollars in actual cash. The said copartnership is to commence on the first day of July, in the year one thousand eight hundred and forty-eight, and to terminate on the first day of July, in the year one thousand eight hundred and fifty-four.

[...]

<Tonight Schulten is to encounter Morphy. He will be the strongest opponent the young hero has yet encountered and I am anxious to see the result. Schulten’s play is of the highest kind. I watched him last night as he played with Perrin and Stanley and I have never seen such games except when Morphy played.>

https://www.chesshistory.com/winter...

Rheinland marriages: married 1851 to Selma Böninger.

Germany, Select Births and Baptisms: at least three children (with names), no dates.

US passport applications in 1848 and 1861
New York Naturalization record oath date 6 July 1848

<There are many games on record by the late Herr Schulten. He was an enthusiast, and played only with first-class players. In Paris, 1865, he appeared at the Cafe de la Regence, and had many a brilliant skirmish with Kolisch and Hirschfeld - the brilliancy, of course, on the side of his opponents. This class of amateurs is now extinct. Herr Schulten was a portly gentleman of the old school, in appearance not unlike the late Prince Bismarck, plus a pair of gold spectacles and a perruque - quite a chef-d'œuvre of a French artist.>