Scholastic: News for your classroom
International Children's Digital Library
Library of Congress - Digital Collections
Ben's Guide to U.S. Government for Kids- Ben's Guide serves as the educational component of GPO Access, the U.S. Government Printing Office's service to provide the official online version of legislative and regulatory information.
the Presidential Poster - (click on the Download link, on the right-hand side) and a corresponding Lesson Plan explaining the road to the White House in a format that is suitable for kids of all ages. Watch the video explaining the election process from national conventions to the election.
Ben’s Guide - https://bensguide.gpo.gov
The Government information for Children [from GODORT] has a site you might like to pull info from - http://guides.ucf.edu/gic
Kids USA - https://kids.usa.gov/
Scholastic's American justice page
Symbols of the United States, a primary source set (The Library of Congress Teachers Page) has good ideas for primary grades. There are many teaching ideas included: the PDF set and resources and the free ebook (you can read this book with iBooks on your iPhone, iPad, iPod touch, or Mac).