The American painter George Innes is an interesting case in point. Innes was born in Newburgh, New York in 1825 so if he wasn't exactly born IN the Hudson River School, he was at least born in the Hudson River Valley. He grew up however in Newark, New Jersey, with access to the best schools of art nearby New York City had to offer. He began painting in the tight, controlled style of the Hudson River School and after having spend a year studying in Italy, found some success by 1855 when he painted Lackawana Valley.
When Innes returned to Europe, he chose to study in France and was especially attracted to the Barbizon School (roughly the French equivalent of the Hudson River School but with a greater emphasis perhaps on painting in the out of doors). There his painting style loosened up as he studied with Theodore Rousseau. Rousseau's influence can be seen in Innes' Delaware Water Gap of 1861, painted upon his return to America. But Innes' move to nearby Eagleswood, New Jersey, and his interest in spiritualism, had more to do with evolution as an artist than France or the Barbizon. There his depiction of nature, a tree for instance, was no longer treated as a biological specimen but as "merely" a patch of green or brown pigment augmented by sympathetic harmonies of color stretching across the picture. His 1891 painting, Early Autumn, Montclair is so much softer, so radically different from the Delaware Water Gap of some thirty years earlier they would seem to have been painted by different artists. In reality, they were. In thirty years, Innes had BECOME a different artist.