Learn about the 50 states! Factmonster.com
Links to the 50 state websites! Kids.usa.gov
Enchanted learning - learn about the 50 states! 

Geography

Latitude Longitude Locator

Bill of Rights

Bill of Rights Match Game

How a Bill Becomes a Law

Ben's Guide - How Laws are Made

Three Branches of Government

Thinkquest

Ben's Guide

Congress For Kids

Fact Monster

Truman Library

USA.gov

Other:

My Wonderful World for Kids - National Geographic - Geography is thrilling, isn't it?

The US 50 - Everything you need to know about the 50 states. 

Puzzled States

WorldAtlas.com - Great resource for maps!

Ben's Guide to U.S  Government

Ben's Guide - Branches of Government

PBS Kids - The Democracy Project

Constitution Center - Explore this interactive U.S. Constitution. 

Whitehouse 101 - Fun and facts for all ages. Official site of the White House. Lots of information about past presidents. Make sure to check out the first pets!

Time for Kids - Current Events

Flags of the World - About.com