Placitas Community Library: "Una placita para todos"

I've been fortunate to make a number of library visits. These include the Biblioteca Jaume Fuster (Library Visit #12; Barcelona, Spain), Spanish National Library (Library Visit #13; Madrid, Spain); Killeen (Texas; Library Visit #14) Public Library; Millwood Branch of the Austin Public (Library Visit #15), and the tribal community library at the Pueblo of Cochiti (Library Visit #16). I made return visits this past week to the libraries at the Pueblos of Sandia and Santa Domingo.

Yesterday I was fortunate to visit the new Placitas (New Mexico) Community Library (Library Visit #17). Now, in its third year of operation, the Placitas Community Library serves a community of over 6000 individuals. The library's mission is "to provide a hub for library services and activities connecting our community to the world in a warm and friendly environment." Staffed by an able corps of volunteers (including two librarians with MLS degrees, one of whom also has a PhD), the Library offers a full range of services including summer reading program, ILL, reading clubs, public access comuting. The library's located in an unincorporated area and thus receives no tax support. Placitas has a Board and Friends group. They are in the process of locating funds to construct their own library building; the library currently is located in a former transmission shop and is welcomed by its users.

This brings to mind a number of questions:
How many US libraries are staffed entirely by volunteers? How are public libraries in unincorporated areas funded? How do such libraries raise funds for construction projects? What sources fund general operating expenses?