Rule VII.—Many special names of a common kind are, in particular uses, treated as proper nouns and capitalized.
Examples:—Congress, Parliament, Senate, House of Representatives, State (for one of the United States), Hudson River Railroad, Aldine Printing Company.
Capitalize the names of political parties; as, Republican Party, Democratic Party, Progressive Party, etc.
Capitalize Christmas Day, New Year’s Day, Lincoln’s Birthday, Washington’s Birthday, Good Friday, Decoration Day or Memorial Day, Fourth of July, Labor Day, Election Day, Thanksgiving Day, etc.; a noted day, as Black Friday, etc.; but blue Monday.
Capitalize Northerner, Southerner, Northern gentleman, Southern blood, etc.
Capitalize names of important events and periods: as, the Creation, the Fall, the Flood, the Reformation, the Revolution (French or American), Civil War (American), the Middle Ages, the Union, Reconstruction.
Capitalize religious denominations; as, Methodist, Episcopal Church, St. Mark’s Church, Church and State, etc.
Church is without the capital always when used alone or when meaning congregation or building; as, a Methodist church in Hoboken.
Capitalize College, Club, Society, etc., when referring to that particular body, in by-laws, proceedings, or other publications of a college, club, society, company, etc.
Capitalize Monsieur, Madame, Signor, etc.