Even if one hasn't read the novel, anyone who's seen the 1960 Disney classic starring Hayley Mills already knows this. Of course, as with any Disney movie, there are significant differences between it and the original text.
I can often remember when I discovered the differences between Disney adaptations and the tales they're based on; I still remember how horrified I was when I read what really happens to the little mermaid. Although the Disney film Pollyanna is 'inspired by' rather than 'based on' Porter's novel, I think the spirit of Pollyanna transcends the textual contentions and comes through in the music, colors and All-American tone that is the hallmark of post-war Disney. And the ingenue Hayley Mills is incomparable, which is why I never understood Disney's reasons for re-making The Parent Trap.
Although Littleton doesn't offer much more as a tribute to Porter than a statue (no preserved home or museum of literary artifacts to peruse), it's worth a day trip to say you've been in The Glad Town.