My wife she refuses to wear the Shari'a custom of dress and I am living in the USA and the law here with her. We keep fighting about her dress.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

It is your duty to do your best to improve your wife and make her good by all legal means such as admonition and leaving her alone in bed. If you get no benefit from these two actions, then you can beat her lightly if you can and, if such an action does not constitute harm to you in front of authorities.
On the other hand, if the above-stated ways are fruitless, then part from her, since a wife who refuses to put on Hijab after the above-mentioned means of treatment is not a good woman. There are many other women.
Here, we draw your attention to the Shari'a ruling concerning residence in non-Islamic countries. Please, consult our Fatwa: 83806.
Allah knows best.