"further" and "furthest" in AmE?

hello,
I've read in a book that "further" and "furthest" are only used in BrE, that Americans only use 'farther" and "farthest". Is that true or are "further" and "furthest" less common in AmE?
Thanks for helping!

I think further is more common than farther in the US. They are used in different contexts, though.

1. California is really far from here, but I Arizona is even farther.

2. I want to go further with my career.

Usually farther is used for geometrical distance, and otherwise further is used.

"I think further is more common than farther in the US. They are used in different contexts, though." Are you sure? I thought it was the contrary!

ooh sorry the last posted was me!

I don't believe there is any difference.
Each is the inflected form of the other one.

"further" and "farther" are often used interchangeably by many Americans.

I myself tend to far more heavily use "further" than "farther" in speech, actually using "farther" in speech quite infrequently. I am not quite sure how frequent the two are used by others here in southeastern Wisconsin, but I do not really recall hearing "farther" much in practice myself.

I use farther and farthest only with respect to distance. Further and furthest are more general and I use them in many contexts. I haven't noticed American such as myself using the latter any less often than the British, but then again I haven't listened for it, either.

thanks a lot for all your posts. So according to your posts "further/furthest" are the most used, right?
and "farther/farthest" are only used referring to distance?

I don't know that you can say one is used "more" than the other. Larissa. But no, your book was completely wrong.

You should also take into consideration that "further" can also be used as a verb, as in "He tried to further his own interests by cozying up to his girlfriend's wealthy father."

And you CAN use both words to refer to distance, whether geographical or metaphorical -- "further down the road" and "farther down the road" are identical in meaning, as are "further down the line" and "farther down the line." So don't sweat the distinctions!

Thanks Uriel for the explanation