What does America have to do with it?

That isn't a specifically American tradition.

Also, how do you know where OP is from?

.

http://en.wikipedia.org/wiki/Onychectomy

Although common in North America [and Asia] elective declawing is considered an act of animal cruelty in many countries.

Declawing is legal in most US jurisdictions. It is estimated that 25% of owned cats in the United States are declawed.

On the other hand...

In many European countries the practice is forbidden either under the terms of the European Convention for the Protection of Pet Animals or under Local Animal Abuse Laws, unless there it is for "veterinary medical reasons or for the benefit of any particular animal."

Some European countries go further, such as Finland, Estonia, the Netherlands, Germany and Switzerland, where declawing cats for non-medical reasons is always illegal under their laws against cruelty to animals.

In the United Kingdom, declawing was outlawed by the Animal Welfare Act 2006. Even before the 2006 Act, however, declawing was extremely uncommon ... the procedure was considered cruel by almost all British vets, who refused to perform it except on medical grounds.