[Devora]

You do not need anything. (Which, to me, is a little bit concerning because the assumption is that a child with an adult belongs with them.) However, a colleague of mine who has a child who is adopted transracially said he always took her birth certificate with him (the amended one) because they were occasionally questioned while traveling in the US. Mind you, she's in college now so when she was younger there was much less awareness of adoption. Their family was additionally conspicuous because they have two daughters, one of whom was a different apparent ethnic/racial background and the other who was not.

I think these days there's so much more awareness of adoption that it's less likely to be an issue, but just in case we do bring our son's US birth certificate with us when we travel domestically.

Another issue to consider as your child gets older, especially, is the possibility that your child may be scrutinized due to anti-immigrant biases. When my sister-in-law who is Hispanic travels near the border she has a copy of her birth certificate and marriage license with her. More than once she has been stopped and questioned by immigration officials simply because she is Hispanic. (She thinks she's more conspicuous because her husband is white.) It's not happened often, but enough that she keeps the documents with her. This isn't likely to be an issue for your child traveling with you right now, but I put it out there as something to consider. Having a birth certificate or US passport with you is a quick way to end the questioning.