This is the single family that makes up the order Gaviiformes.
The five species of the family that can be spotted within North America (and northern Eurasia) are:

Red-throated Loon
Pacific Loon
Arctic Loon
Common Loon
Yellow-billed Loon
The photography goals for this family are basically: getting a picture of each member (I’m currently a fifth of the way there), getting a picture of a parent and young, and getting a picture of one taking off (or landing) on a lake/river. The big bonus would be getting an audio recording of them on a lake in the northern part of the country.