Follow the Money
From the National Institute on Money in State Politics. Track contributions to candidates and committees, by interest group, to the district level. See also their reports by subject, e.g. immigration.
Public Opinion Surveys with State or Regional Emphasis
from Cornell University
Election Administration Resources on the Internet
Comprehensive listings of U.S. federal, state, and local elections offices
Council of State Governments on Elections
National Governors Association--Elections
National Conference of State Legislatures
2011 State and Legislative Partisan Composition
Legislatures and Elections section
Pew Center on the States Election Initiatives
Mayoral Elections Center
The U.S. Conference of Mayors (USCM) is the official nonpartisan organization of cities with populations of 30,000 or more. Site allows you to search past election results and view scheduled elections.
electionLine.org
news and analysis on election reform
Ballot Watch
Browse reports or search a database for details about pending or qualified initiatives and referendums on state ballots.
Statistical Abstract of the US, Elections section
includes data on gubernatorial races and state legislatures
America Votes
Compiled biennially since 1956 (print).
State by state voting statistics for presidential, congressional, and gubernatorial elections, including primaries.
The Almanac of State Legislative Elections : voting patterns and demographics 2000-2006
and State Legislative Elections: Voting Patterns and Demographics [1990s] 1998 e-book link
Data and analysis on state legislative elections from CQ Press