If it is a row house the joist should span party wall to party wall yes however sometimes they spin the framing and support it different ways. Sometimes what should be logical is not so MAKE SURE that it is not load bearing. If it is load bearing there may be framing in the same location on all levels which can be a hint that there is load being carried all the way down to the footings.
Good luck on this one as it can get dangerous quite quickly. One way you can possibly analyze that header and see what is in the wall without opening it up is remove the top piece of casing and peek up above the door jamb you will either see 2x on flat which will probably tell you it is also not load bearing or double 2x with possibly spacers sandwiched in between which may tell you it is load bearing however there is no fast hard rule on how they may have framed it. If you can get above the wall (maybe there is an attic as stated previously) where you can see what is above then you will be even more informed as to what you have.
Take care and be safe!
Good luck on this one as it can get dangerous quite quickly. One way you can possibly analyze that header and see what is in the wall without opening it up is remove the top piece of casing and peek up above the door jamb you will either see 2x on flat which will probably tell you it is also not load bearing or double 2x with possibly spacers sandwiched in between which may tell you it is load bearing however there is no fast hard rule on how they may have framed it. If you can get above the wall (maybe there is an attic as stated previously) where you can see what is above then you will be even more informed as to what you have.
Take care and be safe!
