For most Texans, the 2016 election doesn't offer much excitement outside the presidential race.

Only one district is up for grabs, but the race there has the attention of the state and national political parties.

A map of spending by independent political interests in Texas shows 86 percent -- worth $2.4 million -- concentrated in a single gigantic district. Texas' Twenty-third Congressional District stretches some 500 miles from San Antonio to El Paso, and pits Republican incumbent Rep. Will Hurd against former Congressman Pete Gallego.

"It's the closest thing we've got to a fifty-fifty district, in terms of Democratic and Republican representation," said longtime Texas politics watcher and Quorum Report editor Harvey Kronberg, who explains why out of 36 congressional districts in Texas, it's the only one voters are allowed to decide.

"Of course, it always goes back to redistricting," said Kronberg.

Despite gaining four new congressional seats in 2010, thanks largely to growth in the Hispanic community, state lawmakers have managed to keep the competition to a single district that has waffled between Democrats and Republicans every two years.

"In a sense, that tells you everything you need to know about American politics," said Kronberg. "Democrats structurally do better in presidential years because their core constituencies really only pay attention to the top of the ticket, whereas Republicans have a structural advantage in off-year elections because there's no marquee name at the top of the ticket, and redistricting has given them the advantage already. And they're a more organized party, it's easier to turn their people out."

The question is whether Republican presidential nominee Donald Trump will drag the heavily Hispanic district back to the blue column.

Both parties have invested heavily in the race, with U.S. House Democratic Whip Steny Hoyer campaigning for Gallego Thursday in San Antonio while top Republicans raise money that will be channeled to Hurd's aid. By September, Hurd had out-raised and out-spent Gallego by a two-to-one margin. The Republican raised $2.6 million and spend $1 million, while the Democrat raised $1.3 million and spend $557,000.