22 toss-up House races to watch on election night

Election Day is here, and tens of millions of Americans are now heading to the polls across the country.

Their votes will be the deciding factor in 22 toss-up House races that will determine whether Republicans or Democrats control the chamber for the next two years.

Beneath the surface, the battle for the gavel is getting more expensive. House candidates have spent more than $3 billion on their races so far, concentrated in roughly 40 battleground districts.

Arizona's 1st District...