i'm a usa resident not citizen yet...do i need a passport to travel domestic in Usa??

dunno

To travel inside the US no, to travel in and out, the passport from your own country yes....

No, you don't need a passport for domestic travel. However, you should bring your green card.

My sister and I are both residents, too. One fall we drove up to Vermont and got stopped by the border police. I had my driver's license and green card. My sister left her resident card at home, however. The officer said that she should carry it all times. Nothing bad happened. He just looked at her driver's license instead and asked us some questions. Still, I wouldn't want to go through that again.

No. For an alien (and I'm using the word to mean someone who is not a national of the country he/she is in) once you're in the country (using your passport) you're in !! I once went to the US via Hawaii where I made a stop. Going on to US mainland did not require a passport as I had already landed on US soil (Hawaii).

However, aliens should carry their passports as the passports are their only recognised form of identification.

No, you don't need your passport but to board the plane you will need some form of picture ID, such as a US driver's license. If you don't have any other picture ID, then bring the passport with you.