A new study by the National Institute on Money in State Politics finds that the 2007-2008 state legislative campaigns were the most expensive ever, breaking the $1 billion mark for the first time.

Among the report's other interesting findings:

• Only one-third of races nationwide were monetarily competitive.

• Money and incumbency are nearly unbeatable: incumbents with lots of cash won 94% of the time.

• Ballot measures are not grassroots efforts: business and special interests contributed more than two-thirds of all money raised for ballot measures v. 18% from individuals.

• The cost for Tennessee State Senate races for the 2007-2008 cycle was $6.5 million, or $407K per seat.

• The cost for Tennessee State House races for the 2007-2008 cycle was $7.9 million, or $80K per seat.

Here's the full report.