Would a Border Collie Terrier Mix be considered an aggressive dog breed at an apartment?

Sorry, but border collie doesnt go well in smaller place like apartments because those dogs need big fence  yard that can ran around and they use for sports and working breeds and not good living in an apartment. you should find a different place like a house or townhouse, condo or studio that has alot spaces for dog to run and play .not apartment is worst to have a big dog .plus if the dog is aggressive toward of strangers and little children then shouldnt adopt dogs like that if not train well or havent been train . landlords these days does over charge for having pets in apartments. and include some times other states has own law about not allow pit bulls and terriers mix and rottiweriers .. 

Not aggressive, but high energy.  Have to walk them a lot and Border Collies need a job to do - keep them physically and mentally stimulated.

That would depend on how thoroughly you had housetrained and generally trained  the dog, Would it not?

Theres a damn big "Schopf " Right next to the house here:

 Though you ask of apts....

Down in the village where it  my daughter lives in an apt with her man and my grandson. They dont seem to mind her 2 retd sheepdogs at all.

But as i previously said....

That would depend on how thoroughly you had housetrained and generally trained  the dog, Would it not?

Not agressive. But that dog would need a lot of activity. 

They are not on this list of aggressive dogs.  There may be a weight limit you have to abide to.

That's up to the landlord.

What kind of terrier?   Fox terrier and pit bull terrier are two different things.

By who? A landlord? Most landlords will either state pet friendly or no pets...the ones who are pet friendly might ask about the dogs level of obedience//temperament, some might put on a weight restriction, some may want to meet the dog before signing a contract....

A mix of BC and terrier is not a dog that should be kept in an apartment, a mix of breeds that need lot of of excercise, training and work to be happy and healthy......... aggression unless a genetic issue is down to lack of training, lack of socialisation and living with a weak human who has not put in the obedience work   as this mix needs a strong packleader

Not generally, but they often dont meet size restrictions

Often they could be.

Would need hours of exercise and 'work' daily to stop bordem which can cause aggression.

she is a working dog and u will need a backyard for her.