if I'm not mistaken, I think each state is slightly different in how they handle this portion but I'm curious what you Mommas are doing, and what information you have about this topic.
My husband is 50/50 African American, and Caucasian. I am Caucasian. My husband's birth certificate says African American, and would like our LOs to say the same. However in my head I keep thinking genetically, s/he is closer to Caucasian.(if that makes sense, I hope!)
I've seen plenty of interracial families, and know that our babies come out looking really like anything. Some favor their mother's side, others look more like their daddy. I have friends who have multiple children and every one of them varies in their traits. I love the uniqueness they all have.

SO, my question is i guess what would you put as your baby's ethnicity or race when in a "mixed" family? I'm sure as our child grows up, he or she will decide for themself how they would like to be identified but my DH and I still have to pick. Is choosing both an option in today's world? I honestly don't know how it works on official documents.
Wanted to add: I'm not looking for any racist comments or disrespectful words. Keep it adult, keep it clean. I love my family, I love that we may not fit the all the "molds" and I won't tolerate any haters.
Re: Choosing race/ethnicity on the Birth Certificate?
Edit: words are hard on a phone.
If it were me, I'd probably check off "other" or "more than one race," but on the birth certificate, what you're reporting is statistical information, not a determination of LO's ethnic/racial identity. He/she may be born with straight(ish) hair and light skin but still feel strongly connected to the African-American part of your family. Who knows? I'd put whatever you feel is most accurate.
Being that my husband was already raised in an interracial household it's nothing new to him, so I think the majority of it is my own curiosity. Unfortunately, we do live in an area that seems to take a lot of stock into labels, which is odd to me considering we have such a diverse community. (We live in a military town, and see many many different types of families move in and out)
I think we will most likely be going the route of checking both boxes if applicable, it's important to us to have every part of our family recognized not because of the skin tone but because that's who mommy and daddy are. we won't forget about one or the other. Genetically, our babies would be 75% white as previously stated, but I'm just picturing this baby with pretty ringlet curls. (DH and I both have extremely curly brown hair) I can't wait to kiss those sweet cheeks!
I remember the first time race came up with the kids. My nephew (the oldest) asked if he was white or black, so my sister asked him what he thought. He said he thinks he's black like daddy, he thinks his two middle sisters are brown and his youngest sister is white like mommy. Then he announced that they were a rainbow and got all giggly.
The fact that you have to list anything at all is silly, but I'd say do whatever you want.
...And all of my nieces have long beautiful brown curls, one with brown eyes, one with hazel and one with blue...I'm sure your little one will be just as gorgeous, just as you're picturing:)
My short answer - Wow. I find it so crazy that this silly question is still being asked in 2015. Check "other" or "all that apply" - you're carrying the LO and, as mama, you should be represented in whichever silly boxes are checked.
Long answer...
Even outside of the "one drop rule" from the old days, I think parents of mixed race children born in the last 50 years or so have tried to manage their kids' expectations in life by telling them how the world would perceive them. For instance, I think I've read that President Obama's and Halle Berry's white mothers explained to them that the world would perceive them as black, so they should live their lives as such. Meanwhile, more "ambiguous" looking kids like Pete Wentz (Fall Out Boy) and Troain Bellisario (Pretty Little Liars) have to tell you their heritage since you may not be able to tell from their physical features.
I think kids of mixed races born in the last few years are getting the freedom to define themselves (to a point - race is still an issue in America). Millenials and those born after them are more commonly mixed than any other generation, so they put less pressure on themselves to define each other by one race.
The world is becoming more and more of a melting pot and your LO is representative of that - their silly box should be too.
NTNP: May 2015
TTC #1: late August 2015
PCOS Dx: January 2016, starting Femara Feb 2016
BFP: 2/29/16 - Happy Leap Day!
I'm biased, but I like to think my hubby is quite the stud, I'm sure his babies will be gorgeous!
I couldn't recall one on my sons birth certificate either !
California, Pennsylvania and South Carolina have no race one them.
Married 03/18/10
DS #2 Born 05/19/11
DS #3 Due 07/26/15