Bruce Frohnen, The American Nation: Primary Sources (Civil War to WWII)

Bruce Frohnen, The American Republic: Primary Sources (Founding to Civil War)

The Articles of Confederation (html; numbered sections)

The Cambridge Platform of Church Discipline (1648) (many formats, some with page numbers and/or numbered paragraphs)

Constitution of the Confederate States (html, numbered sections)

The Constitution of the United States (with amendments) (html; numbered sections)

The Declaration of Independence (html; short enough that lack of pagination isn't a problem)

The Declaration of Sentiments (Seneca Falls Conference, 1848) (html; no pagination, but short)

The Federalist (many formats, some with page numbers)

Fundamental Orders of Connecticut (1639) (html; numbered paragraphs)

Mayflower Compact (1620) (html; short enough that lack of pagination isn't a problem)