The Eastern Tiger Swallowtail is a common sight in the United States east of the Rockies. It is not necessarily the most common butterfly (Cabbage Whites and the various Sulfurs are more often seen), but it is certainly the largest of the common sights. It is not very picky about what kind of flowers it can be seen on, and it would be strange for a pollinator garden to fail to attract one.
As a side note, as I was typing this up, one of these butterflies flew right up to my window and tried to enter the room. That is how common of a sight they are. I have often been able to easily spot them while driving down the road.
Crayshack 