Will I need to go through immigration when flying from Sweden to Finland?

Question

I will be in Stockholm in January and I'm thinking of taking a flight to Rovaniemi, Finland while I'm there.

I know I will have to go through immigration to get into Sweden. But, since I'm already in the Schengen area, will I need to go through immigration/passport control to fly to Finland, or, will is be considered a domestic/Schengen fight even though it's international?

I doubt this will happen in Sweden, but I've been through immigration before where it took over an hour to get through and then you have to walk an additional 20 minutes to the gate. I want to make sure I allocate myself enough time.

I'm not sure of the airport of departure yet, it will either be Bromma or Arlanda (if that even makes a difference).

Now, I found this question, but that deals with transit. I will be in Sweden a few days before flying to Finland, and then visa versa.

I'm a US Citizen (if that even matters).

Answer 1

The flight from Sweden to Finland is an internal Schengen flight, so you do not go through immigration.

You will likely pass through customs, but as you travel from one EU-Schengen country to an other you can just walk through the EU line if they have one or Nothing to declare if that seems the only or better option, unless you want to ask customs people questions.

Do leave enough time for security, internal Schengen flights have the same security as intercontinental flights.

Your nationality does not matter but the airline may want to check you are in the Schengen area legally, some airlines want you to get your boarding pass stamped with 'visa checked', which may also take some more time.