My mom and I are traveling to NYC together. Can we be together at the border control station or will we have to go one after another?

Your age doesn't matter. Go together. I usually do so. This simplifies the control of the immigration officer, especially if your mother doesn't speak English or if she expect that you will guide her to the city and country.

In any case, to reassure you, you will do some queuing, so check how other people behave. If a new policy is being followed, you will find that other people will be split (from their group).

Short Answer: If you're traveling together, you will go together, regardless of your age.

I've repeatedly flown into the US from overseas, most recently last month. My family is mixed US passport and Green Card, and we don't have the same last name. Regardless, we've always been processed with the automated machines.

If there's someone with a US passport in the group, and everyone else has the required visa, then you all go straight through the automated system. You can choose your preferred language for the process at the kiosk. A non-US citizen will have to submit to a finger print scan at the machine, everyone must answer questions about their trip, and everyone will be photographed. At the end, each person has a printed "receipt" to carry, and eventually give to a customs agent.

You interact with a human afterwards, but almost everything is done by machine.

There's a long queue beforehand, so use the restroom or fill your water bottle immediately after you leave the plane. We've stood in line up to 40 minutes.

Newark is listed as having the Automated Passport Control machines. If you are eligible to use these then...

The kiosks allow people residing at the same address to be processed together.

I believe for visitors that means those who will be residing at the same address (including the same hotel) while in the US, not a matter of living together in your country of residence. Certainly you and your mother should move to a machine together and start entering your details - it will guide you if you need to do anything different

I know the question was about US, but I guess it also depends on the officer's mood. I was travelling to Finland last December on our way to Finland the officer asked us to go border control station together, while on our way back another officer specifically told me to keep the distance between me and the control station while he was looking at my gf's documents.

As others pointed out, age shouldn't matter. If I travel to the USA with my spouse, usually we approach the officer together -- it has never been a problem.

Except the last time. We then flew into JFK, and at that moment, I was a "returning ESTA visitor", and my spouse was not. Which meant, we got sorted into two different lanes.

But if that doesn't happen to you, and you're both queuing in the same lane, just approach the officer together. The worst what will happen is the officer saying one of you have to wait till the other is done.

But it's not always preferred, in my opinion, it depends on the airport and how is the security there.

Someday in Frankfort, I and my brother tried to attend together to the border control officer. but he directly asked to come one by one.

So, I think this situation applies to NY airport since the security level there high.

Not in Sweden, they never ask for that.