Overview: Proposition 50, which will be voted on in November, could significantly change the demographics of California’s Inland Empire, with the share of Latino eligible voters in Rep. Kenneth Calvert’s district rising from 29.7% to 55%. The proposed redistricting measure could also shift as many as five of the state’s 52 House seats from Republican to Democratic control, making several IE seats, including CA-41 and CA-48, more competitive. The region’s closely balanced partisan landscape and high voter engagement mean that the outcome of the measure could hinge on turnout among Latino voters and independent and infrequent voters.
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According to a new Cal Poly Pomona and Caltech joint study that examined Latino voters, redistricting and representation, the Inland Empire could see one of the most significant demographic shifts pending the outcome of Proposition 50. The region’s share of eligible Latino voters in Republican Congressman Kenneth Calvert’s district could rise from 29.7% to 55% – the largest increase of any district statewide.
Why the demographic shift matters in the Inland Empire
By allowing lawmakers to redraw California’s congressional map before 2030, Prop. 50 could accelerate existing shifts in the Inland Empire, grouping different communities together and redefining swing terrain. The outcome could determine whether several IE seats – including District 41, held by Rep. Kenneth Calvert, and District 48, held by Rep. Darrell Issa – remain competitive.
The findings of the joint academic study focus on the potential impact of the proposed redistricting measure on the region’s political landscape, reshaping who holds power in California’s congressional delegation. With this measure on the Nov. 4 ballot, a statewide conversation around representation, voter power and partisan control has sparked. At its core, Prop. 50 centers on timing and control of the map.
Officially known as the Election Rigging Response Act, Prop. 50 would allow state lawmakers to temporarily redraw congressional maps in response to Republican-led mid-cycle redistricting in Texas. If approved, the new lines could shift as many as five of the state’s 52 House seats from Republican to Democratic control.
Two long-time Republican incumbents serving the Inland Empire – Reps. Calvert of Corona and Issa of Temecula – could see their political strongholds reshaped if Prop.50 passes.
Calvert’s 41st District, which stretches across western Riverside County from Corona and Norco through Menifee and Lake Elisonore to parts of the Coachella Valley, has been growing more diverse and competitive. Once reliably conservative, the area has experienced rapid suburban growth, rising house costs and intensifying pressures from wildfires and traffic congestion. Calvert narrowly held his seat in 2024 after a wave of new voters in Riverside and the desert cities cut into his margins.
Issa’s 48th District, which includes Temecula, Murrieta and portions of northern San Diego County, faces similar current changes and those posed by Prop.50 if passed, making Issa’s seat more competitive. Together, these districts paint a picture of how new lines could re-balance once “safe” territory.
Under the proposed redistricting plan, the region would see the largest demographic change in the state. Combined, San Bernardino and Riverside Counties are about 52% Latino, a shift which researchers note could have the potential to sway the region’s electorate toward Latino-majority representation. Under both the proposed and current Prop. 50 maps discussed in the joint study, the Inland Empire includes four Latino-majority congressional districts: 25 (Rancho Cucamonga, San Antonio Heights, Upland) 33 (San Bernardino, Bloomington, Rialto), 35 (Chino, Eastvale, Fontana, Ontario) and 39 (Jurupa Valley, Riverside, Moreno Valley, and Perris). If passed, Prop. 50 would essentially make District 4 the fifth Latino-majority district. In practice, the question stands of which voters get grouped together via districts – and which don’t.
According to poll predictions, the majority of California voters will vote “Yes” on the measure. Locally in the Inland region, a study from the University of California Berkeley’s Institute of Governmental Studies reported that 45% of voters say they would vote “Yes” on California’s proposed redistricting measure, while 39% would vote “No,” and 16% remain undecided. The region’s narrow divide mirrors its closely balanced partisan landscape, where Democrats hold only a slight edge over Republicans. Persuasion and turnout are key factors of whether or not the IE will pass the measure.
While overall support of Prop. 50 trails coastal regions like Los Angeles or the Bay Area, the Inland Empire reminds a crucial swing region where the outcome could hinge on turnout among Latino voters. Twenty-nine percent of Latino voters statewide remain undecided, as well as independent and infrequent voters who have yet to take a position. This unpredictability in the region was demonstrated during the 2024 presidential election when, for the first time since George W. Bush in 2004, a Republican presidential candidate won both Riverside and San Bernardino Counties.
It was by slim margins that Trump won Riverside County, by just less than 12,000 votes at 49.30% to Kamala Harris at 48.04%. In San Bernardino County, Trump won with just over 16,000 more votes at 49.67% compared to Harris at 47.53%. Trump won 13 cities across the region that he lost in 2020. These numbers indicate just how thin the electoral margins can be in the region.
The Murrieta-Temecula Republican Assembly (MTRA), a chapter of the California Republican Assembly, said it has endorsed the “No on Prop. 50” campaign, maintaining that the mid-cycle redraw would divide Inland Empire communities by geography and zip code to consolidate Democratic power.
“Despite California having a Democrat majority status, lots of voters and residents living throughout the Inland Empire, and also the California Central Valley agricultural regions, have very different and more traditional perspectives and values than the coastal elite residing in Democratic strongholds like Los Angeles and the San Francisco Bay area,” wrote Rick Reiss, vice president of the MTRA, in a statement.
Reiss also shared MTRA’s perspective that even if Prop. 50 passes, GOP seats are not guaranteed to flip, citing voter frustration with one-party control and a desire to reclaim natural rights and freedoms.
According to a recent report about the special election from the California Secretary of State, Riverside and San Bernardino Counties reflect high voter engagement with over 2.6 million registered voters combined. Registration levels help set the stage for how much change is possible.
Riverside County has 1,424,052 registered voters – 38.1% Democrats and 32.5% Republicans – while San Bernardino County has 1,242,464 registered voters, including 38.6% Democrats and 30.9% Republicans. Both counties demonstrate registration rates above 80%, indicating a closely divided but slightly democratic leaning electorate. In both counties, just over 20% of registered voters have no party preference. This large no-party preference bloc remains the wild card.