WASHINGTON (CNN) -- Candidates, political parties and interest groups spent over $2.1 billion in television advertising in the two-year election cycle that just ended -- a record breaking amount in any presidential or midterm election, according to a study by TNS Media Intelligence/Campaign Media Analysis Group, CNN's consultant on political ad spending.

More than half of this amount ($1.1 billion) was spent in the final 30 days of the campaign.

The 36 gubernatorial races held this year accounted for $652 million in ad spending, compared to $391 million spent on U.S. House races and $365 million spent on U.S. Senate races. An additional $302 million was spent on TV ads regarding various state ballot measures across the nation.

The incoming freshman class in both the Senate and the House spent at least a combined $110 million in TV ads to win office. Those ads mainly addressed the Iraq War ($32.3 million), taxes ($29.1 million), health care ($22.6 million) and energy ($12.6 million).

The first ad of the campaign season aired in Phoenix, Arizona, on January 18, 2005, approximately 21 months before Election Day in that state's race for governor. The final ad of Election 2006 aired Tuesday in San Antonio, Texas, for a run-off election in the state's 23rd congressional district.

The final ad to air on Election Day on November 7 ran in Evansville, Indiana, five hours after polls had closed in that state.

The previous record for political ad spending was $1.7 billion in the 2004 election cycle. The previous ad spending record for a mid-term election cycle was $1 billion in the 2002 campaign.