Iowa

Congressional Districts 2012 Census Results, U.S. Census Bureau

.The all candidate summary file contains one record including summary financial information for all candidates who raised or spent money during the period no matter when they are up for election.

Every two years, the Commission publishes Federal Elections, a compilation of the official, certified federal election results obtained from each state’s election office and other official sources.

Data cited at: RCP https://www.realclearpolitics.com/epolls/2020/senate/az/arizona_senate_mcsally_vs_kelly-6801.html  Data for Nov-3-2020 Values are Final Results. 

The US Presidential election takes place every 4 years and Congressional election happens every 2 years. National elections generally fall into two categories: elections where congressional seats are the highest offices decided and years where voters decide on the office of the President and congressional seats.To avoid confusion with presidential elections, the source refers to non-presidential year elections as “congressional elections" and the data is published at 4 years interval Reference link: https://www.census.gov/library/publications/2015/demo/p20-577.html

Data cited at: RealClearPolitics- https://www.realclearpolling.com/polls/president/general/2024/trump-vs-biden