The Western Confucian notes an article on the St. Louis Hegelians. The place of the St. Louis Hegelians in American thought has not, I think, been properly studied and appreciated yet; founded by William Torrey Harris and Henry Conrad Brokmeyer, the movement essentially mediates between two much better known philosophical movements, the Transcendentalists on the earlier end and the Personalists and the Pragmatists on the later end, pretty much created the idea of a Philosophy Department (as opposed to seeing philosophy as a general framework for education) and of academic philosophy as a profession (although the movement was not by any means confined to academia the way philosophy now often is), and established a considerable amount of the nineteenth century intellectual infrastructure of the United States.
Hegelianism is not especially popular these days, despite some small resurgences of interest, but this was not true in the nineteenth century; Germany had its Hegelian turn and Britain had its Hegelian turn, so it's actually unsurprising that America had one as well. The Hegelianism of the St. Louis circle is often said to have had no lasting effect on the intellectual life of the nation, but I think this is almost certainly false (and particularly when it comes to how the nation thought about matters of education, of ethics, and of itself). But it is certainly true that the courses of its influence are largely unstudied and therefore largely unknown; there's a great deal of guesswork involved at present.
It's the institutional effects that are easiest to trace. The existence of kindergartens in the U.S., for instance, is largely due to Susan Elizabeth Blow, one of the more important members of the St. Louis circle. The idea of a kindergarten had been developed by the German philosopher of education Friedrich Froebel under the influence of Romantic ideas. The kindergarten did not easily take off in any of the German states at the time: it was regarded as subversive of the institutions of society and Prussia, for instance, outlawed them, claiming that they cultivated atheism and demagoguery (Froebel's defenders held that Prussia did this because the education minister was so stupid that he confused Froebel with another Froebel who was a notorious atheist). Things were better in Froebel's native Thuringia, but the spread was still rather slow. A few kindergartens were established here and there in the U.S. by people influenced by Froebel's ideas, but it was Blow who turned it into a movement, adapting it to American conditions, developing Froebel's theories, and turning the U.S. kindergarten movement into one of the major educational projects of the day. From that point on the idea of the kindergarten spread all over the world. But it is a notable and interesting fact that kindergarten teachers were originally taught their trade by Hegelians, on Hegelian principles.
Other institutional influences can be found. The Scotsman Thomas Davidson returned from St. Louis to Britain and founded a society, the Fellowship of New Life, which included such notables as George Bernard Shaw and Havelock Ellis. A falling out over the mission of the society -- a number of the members thought Davidson put excessive emphasis on the spiritual at the expense of the material -- led to the formation of the Fabian Society.
In this day and age it's pleasantly easy to uncover many of the works of the St. Louis Hegelians; here is just a handful of works available at Google Books (many of them could also be found at the Internet Archive) by some of the more important or notable St. Louis Hegelians.
William Torrey Harris, The Theory of American Education
William Torrey Harris, Hegel's Logic
Denton Jacques Snider, The State, Specially the American State, Psychologically Considered
Denton Jacques Snider, Abraham Lincoln: An Interpretation in Biography
Denton Jacques Snider, Social Institutions in Their Origin, Growth, and Interconnection, Psychologically Treated
Denton Jacques Snider, The Psychology of Froebel's Play-Gifts
Denton Jacques Snider, The St. Louis Movement in Philosophy, Literature, Education, Psychology, with Chapters of Autobiography
Susan Elizabeth Blow, Educational Issues in Kindergarten
Susan Elizabeth Blow, Symbolic Education: A Commentary on Froebel's 'Mother Play'
Susan Elizabeth Blow, Letters to a Mother on the Philosophy of Froebel
Susan Elizabeth Blow, A Study in Dante
Marietta Kies, Institutional Ethics