All or parts of 29 counties are home to about 726,000 residents in an area bigger than most states east of the Mississippi River.
Politically, the 23rd is one of the most competitive districts in the country. It has changed hands every time since it was last redrawn in 2011. Pete Gallego, a Democrat, is trying to take the seat from Republican Will Hurd, who two years ago took the seat from Gallego. The Democrat says competitiveness is good in a political universe where everything seems so polarized.
In theory, the largely rural 23rd was drawn to favor a Latino candidate. About 70% of the residents are Hispanic.
But Gallego sees another reason he failed to win two years ago. "Really, the problem has been turnout and this perception that whoever wins doesn't matter." He says Latinos came out to vote in 2012 during a presidential election, but participation dropped in 2014 when he lost the seat by about 2,500 votes. (Rep. Hurd did not reply to several requests for an interview for this story).
According to a study by The City University of New York commissioned by CNN en Español, 40% of Texans identify themselves as Latino, twice as many as in 1990. The number of eligible Latino voters in the state stands at 28% of the electorate -- but the CUNY study concludes that in this state, Latinos register to vote at a lower rate than the national average for this group. Only 39% of the Latino electorate likely will vote in November.
And though Latinos in Texas seem to favor Democratic candidates, their lack of participation seems to be part of the reason Republicans continue to control the Lone Star State, according to the same report.
Others, such as Jose Garza, an attorney for the Mexican American Legislative Caucus, say Latino and minority voters have historically been disenfranchised.
"People have to understand the history in Texas," Garza says. "Officials in Texas both Republican and Democrat have used the Latino voters for their own advantage and discourage Latino and minority voters from participating."
Garza says the 23rd district is a good example of how state officials drew boundaries that included a high percentage of Latinos who couldn't vote because of age or legal status. "So on paper it looks like a solid district but in practice they manipulated the data in order to make sure that that district did not elect a Latino-preferred candidate -- not a Republican or Democrat, a Latino-preferred candidate."
After the 2010 census, Texas gained four additional congressional seats based on the increase of the population largely among Hispanics. The Republican-led Legislature drew new maps that were rejected by a federal court of appeals, which said the maps diluted the influence of minority voters. A three-judge panel drew new districts that in turn were rejected unanimously by the Supreme Court, leaving in place the original maps.
Having sufficient campaign money is another obstacle for Latino candidates to reach higher offices in the state.
Cesar Blanco, interim director of The Latino Victory Project, a group dedicated to help financially Latino candidates in the country, says both major parties have failed to put money behind Latino candidates in Texas, the way they've done in Florida and Nevada, critical swing states.
"We need to work with national groups to get more resources."
Texas has few statewide Latino elected officials. Sen. Ted Cruz and Texas General Land Commissioner George P. Bush are the highest ranking Latinos in the state. Bush is the son of former Florida governor Jeb Bush; his mother Columba was born in Mexico.
Pete Gallego sees this election cycle with renewed optimism. He expects Latinos will vote in "self-defense" because of the way presumptive Republican nominee Donald Trump talks about them.
But Republicans are not ready to concede the district. As of March, Hurd had raised more than $2 million for his campaign -- twice that of Gallego's war chest. Hurd did well in 2014 in more affluent portions of San Antonio and in areas around military bases.
Money is extremely important in a district the size of the 23rd with no dominant TV market, forcing candidates to spend money in more regions of the district.