What was the influence of Jane Austen on American authors?

This is an interesting question, as most often we trace Austen's influence on other British writers, such as George Eliot, who was influenced by her realism. The American writer who first comes to mind, however, as an early fan and advocate for Austen was William Dean Howells. His good friend Henry James was also influenced by her work. James wrote quite a bit about her, some of it critical, but it is clear he studied her carefully and incorporated her realism and cool detachment into his own novels.
Mark Twain, in contrast, famously criticized her. He said he hated her novels, which he saw as out of the American literary tradition, but he also exaggerated his dislike of her as part of a running public debate with Howells.
With the explosion of interest in Jane Austen in the last 40 years has come a profrusion of American written sequels, prequels, and take-offs of her work—the most popular probably being Pride and Prejudice and Zombies.