Links

History

This is one of the best all around sites that I have found. It is titled "The MacTutor History of Mathematics Archive."
http://www-history.mcs.st-and.ac.uk/~history/

This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu/

Reference Topics

This site gives apportionment data using the 2000 census.
http://www.census.gov/population/www/censusdata/apportionment.html

This site gives a nice overview of apportionment methods.
http://www.ctl.ua.edu/math103/apportionment/appmeth.htm#Apportionment

You can find the reference to Article 1, Section 2 of the United States Constitution (among many other interesting things) at this site:
http://www.law.cornell.edu/constitution/constitution.articlei.html

This excellent site from the Census Bureau does a nice historical overview of apportionment in the House of Representatives.
http://www.ctl.ua.edu/math103/apportionment/apphisty.htm

Data from the first federal congress can be found here:
http://www.gwu.edu/~ffcp/exhibit/p14/