Describing dress codes for men travelling on business in the States can be a risky business. It is far more difficult to generalise on this subject than for just about any other major industrialised nation.
Dress will vary from the formal, dark business suit, shirt and tie to literally T-shirt and shorts.
One general dictum could be that the further West you are doing business, the more likely you are to encounter informal dress in business – but this is not always the case.
The best advice would always be to check before departure with others who have visited your particular destination – failing that take a variety of types of clothes to meet all eventualities.
Dress code for women is as varied as that for men and the above advice would hold true.