More than $42 million has been spent on Illinois' top six congressional races in an effort to sway voters.
National political parties and super political action committees have spent almost four times as much compared with two years ago.
Illinois is important in the battle for control of the House, as Republicans try to hold on to seats won in 2010 and Democrats try to pick up 25 seats nationwide to regain control.
Spending was heaviest in the 17th District race between freshman GOP Rep. Bobby Schilling and Democrat Cheri Bustos.
Outside spending reached $8.7 million in the 11th District, $6.6 million in the 12th District, $6.4 million in 10th District $6.3 million in the 13th District and $5.5 million in 8th District.
