SAINT LOUIS, June, 1846. The River Queen, as Saint Louis is sometimes called, is looked upon as the threshold leading to the wild and romantic region of the Upper Mississippi. It was founded in the year seventeen hundred and sixty-four, by two Frenchmen, named Laclade and Chouteau, who were accompanied by about thirty Creoles. The first steamer which landed here came from New Orleans in the year eighteen hundred and nineteen; but the number now belonging here is rated at three hundred, many of which are unsurpassed in speed and splendor of accommodations. The population of this city amounts to forty thousand souls. It is elevated some eighty feet above the low-water mark of the Mississippi, and from the river presents a handsome appearance. The old part of the town is inhabited by a French population, and is in a dilapidated condition; but the more modern portion is distinguished for its handsome streets, and tastefully built mansions and public buildings. Fronting the levee or landing are several blocks of stone stores, which give one an idea of the extensive business transacted here. On one occasion I saw this wharfing ground so completely crowded with merchandise of every possible variety, that travellers were actually compelled to walk from the steamboats to the hotels. This city is the home market for all the natural productions of a wilderness country extending in different directions for thousands of miles, and watered by several of the largest rivers in the world. Its growth, however, has been somewhat retarded by the peculiar character of its original inhabitants. The acknowledged wealth of many of its leading men can only be equalled by their illiberality and want of enterprise. But time is committing sad ravages among these ancient citizens, for they are, from age and infirmities, almost daily dropping into the place of graves. Under the benign influence of true American enterprise, this city is rapidly becoming distinguished for its New England character, in spite of the retarding cause alluded to above, and the baneful institution of Slavery. In fine, it possesses, to an uncommon degree, all the worthy qualities which should belong to an enlightened and eminently prosperous city.