(federal) = federal holidays, (state) = state holidays, (religious) = religious holidays, (week) = weeklong holidays, (month) = monthlong holidays, (36) = Title 36 Observances and Ceremonies Bold indicates major holidays commonly celebrated in the United States, which often represent the major celebrations of the month.
This template's initial visibility currently defaults to autocollapse, meaning that if there is another collapsible item on the page (a navbox, sidebar, or table with the collapsible attribute), it is hidden apart from its title bar; if not, it is fully visible.
To change this template's initial visibility, the |state=parameter may be used:
{{Public holidays in the United States|state=collapsed}} will show the template collapsed, i.e. hidden apart from its title bar.
{{Public holidays in the United States|state=expanded}} will show the template expanded, i.e. fully visible.