Are dual US citizens affected by President Trump's ban on Iran, Iraq, Libya, Somalia, Sudan, Syria, Yemen?

You should certainly be concerned, and not necessarily trust that you will have a smooth time through customs.

Firstly, a statement from the State Department has been made that:

Trump Visa Ban Also Applies to Citizens With Dual Nationality, State Department Says

“Travelers who have nationality or dual nationality of one of these countries will not be permitted for 90 days to enter the United States or be issued an immigrant or nonimmigrant visa,” a State Department official said.

It also applies to people who originally hail from those countries but are traveling on a passport issued by any other nation, the official said.

While it is absolutely impossible that this statement includes US Citizens, the fact that the policy was implemented and rolled out as an emergency measure means you would be at the mercy of the current immigration official's understanding of that. They will be stressed, harassed and miserable, unsure of the rules, and inclined to play it safe. And your needs will be secondary to theirs.

As practical advice, I would ensure you travel with a fellow native-born single-citizenship US citizen whom you trust, preferably Caucasian, who should accompany you if you are detained.

This will effectively give you a second person to act as a "known figure", and whose citizenship status will not be in question by the authorities.

Basically, treat the current situation as if you were in unsafe territory, with poorly defined rules. Hopefully, you will stroll through brandishing your US passport, secure in your citizenship. If you are arbitrarily detained, your ally can relay messages, and ensure you are not accidentally lost in the system.

I am obviously terribly sorry that you have to put up with this, and hope it all goes well for you.

Ongoing details can be found here.

Your concern is valid. Although the executive order did not specifically state anything about US Citizen who also hold another citizenship from one of the seven countries listed by Donald, the implementation of this order is carried out poorly. Remember that a lot of the officers at the airport are not highly educated and you will be at their mercy. Some are really nice, but you never know who you get!

I share a similar concern and I'd rather cancel my trip and lose some $ to being harassed on my way back in.

I advise you hold on your travel plans until further time.

My wife's mother is from Iran. She is also a United States citizen. She will go back and forth to USA/Iran since family is still there.

My wife's mother just tried coming back into the USA and they denied her entry stating she was in Iran for too long. She's had dual citizenship for 10 years and this is the first that this has ever happened.

It's quite ridiculous honestly and I'm not sure what my wife and her mother are going to do at the moment.

Not sure if this is legal but most definitely just happened to them so I would say it does affect people that have citizenship in the USA.