The National Conference of State Legislatures' website has a breakdown of all of the laws regarding the protection of breastfeeding in public and other matters related to breastfeeding.
I am excited to learn that the Patient Protection and Affordable Health Care Act signed into law March 2010 requires employers to provide break time for a lactating mother to pump her milk for up to one year after the birth of her baby. Employers of 50 people or more have to provide some place other than a bathroom stall, by the way.
It is Federal Law that your employer must accommodate your need to feed your baby. View this PDF file on the Department of Labor's website for details.
Forty-four of the states in the US have laws protecting your right to feed your child anywhere in private or public space. Awesome!
The states that do NOT specifically protect the right to feed your child in public are:
Michigan and Virginia have laws protecting breastfeeding from public indecency laws, but that doesn't mean you won't get kicked out of a restaurant for nursing your baby at the table, though.
Nebraska and Idaho exempt breastfeeding mothers from jury duty, but not much else.
If you live in one of these states you should write your state legislators and ask for a law that protects your right to feed your baby in a public area.
If you have been hassled in public about breastfeeding, don't put up with it!