American TV viewers have endured nearly a million political ads between August and October in the run-up to this month's mid-term elections, according to Nielsen Media Research Monitor-Plus.

The US TV ratings measurement body counted 942,900 political ads on local TV between August 1 and October 15, up 31% from a comparable period in the last mid-term election year, 2002.

"Political advertising increases this mid-term election year can be attributed to two main factors: Together the Republican National Convention and the Democratic National Convention have shown a 130% increase in ad activity over 2002, and there has also been significant growth in advertising related to the various ballot initiatives across the country," said Brian Lane, senior VP for client strategy and product marketing at Monitor-Plus.