AP analysis shows Texas and California redistricting efforts could mess
with rare partisan balance
[August 23, 2025]
By DAVID A. LIEB
As Texas Republicans and California Democrats redraw U.S. House
districts to their advantage ahead of next year's elections, they're
potentially disrupting a rare partisan balance in American politics.
The 220-215 majority that Republicans won over Democrats in last year's
elections almost perfectly aligns with the share of the vote the two
parties received in districts across the U.S., according to an
Associated Press analysis. Although the overall outcome was close to
neutral, the AP's analysis shows that Democrats and Republicans each
benefited from advantages in particular states.
The AP used a mathematical analysis designed to measure how many more
U.S. House seats political parties won in each state beyond what would
have been expected from the share of the vote they received. The
analysis showed a significant political tilt in one-third of the states’
congressional districts, with either Democrats or Republicans winning at
least one more seat than expected.
Where do Democrats hold the biggest edge?
In California, Democrats won 43 of the 52 seats last year — about six
more seats than would have been expected based on the average share of
the vote for U.S. House candidates of each party. That was the biggest
gain among all states.
At the urging of Democratic Gov. Gavin Newsom, California lawmakers on
Thursday approved a plan to redraw the district lines created by an
independent citizens commission after the 2020 census. Their goal is to
give Democrats a better shot at winning five additional seats in next
year's elections — countering a similar move in Texas backed by
President Donald Trump.
California's redistricting plan still requires approval in a special
election.
The AP's analysis found that Democrats won about three more seats than
expected in Illinois last year and about two more seats each in
Washington, Massachusetts and New Jersey.
Where do Republicans hold the largest advantage?
In Texas, districts were drawn after the census by the Republican-led
Legislature and approved by GOP Gov. Greg Abbott. Republicans won 25 of
the 38 House seats last year — nearly two more seats than would have
been expected based on their average share of the vote.
At the prodding of President Donald Trump, the Legislature is drawing
new House districts giving Republicans a shot at winning five more seats
in the 2026 midterm elections.
Elsewhere, the AP's analysis found that Republicans won about
two-and-a-half seats more than expected last year in both Florida and
North Carolina and nearly two extra seats in Wisconsin.
How has partisan advantage changed over time?
The number of states with congressional districts tilted toward one
party or another was higher last year than in either of the past two
presidential elections. But those state-by-state advantages essentially
canceled each other out.
When adding results from all states, the AP's analysis showed that
Democrats nationwide won about one-half seat more than expected last
year. Because congressional seats aren't allotted by fractions, the net
result was that each party's share of House seats essentially aligned
with their share of the votes.
"If you look at the actual congressional results, that map looks pretty
darn good at the national level,” said Chris Warshaw, a political
scientist at Georgetown University who is an expert in analyzing
legislative districts for partisan advantage.
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Rep. Mike Olcott, R-Fort Worth, looks at a redrawn congressional
district map as its proposal is debated in the House Chamber at the
Texas Capitol in Austin, Texas, Wednesday, Aug. 20, 2025. (Mikala
Compton/Austin American-Statesman via AP)
That’s a sharp contrast with other recent elections. In 2020,
Republicans won about 10 more House seats than expected based on
their share of the vote in that year's election. In 2016,
Republicans won about 25 more seats than expected. Both of those
elections were held under congressional maps drawn after the 2010
census.
Districts redrawn based on the 2020 census were first used in 2022
and normally would remain in effect until after the 2030 census. But
in some states, there is nothing that prevents politicians from
redrawing districts in the middle of a decade, as Texas and
California are doing.
How does one party gain an edge over another in House districts?
In many states, U.S. House districts are drawn by the state
legislature and subject to approval by the governor. If a political
party controls both the legislature and governor’s office — or has
such a large legislative majority that it can override vetoes — it
can effectively draw districts to its advantage. This is referred to
as gerrymandering.
The legislative author of Texas' new congressional districts,
Republican state Rep. Todd Hunter, made that point clear during
debate: “The underlying goal of this plan is straightforward —
improve Republican political performance,” he said.
One common method of gerrymandering is for a majority party to draw
maps that pack voters who support the opposing party into a few
districts, thus allowing the majority party to win a greater number
of surrounding districts. Another tactic is for the majority party
to dilute the power of an opposing party’s voters by spreading them
so thinly among multiple districts that it's extremely difficult for
their preferred candidates to win.
Political advantages also can develop naturally. When politically
like-minded voters live in the same area — such as urban Democrats
or rural Republicans — it can create an edge for the parties even if
there is no intent to gerrymander districts.
California's citizen redistricting commission did not use political
data when drawing districts yet still ended up with a U.S. House map
favoring Democrats.
“Unless you kind of hardwire in some metric of fairness that has to
be met by the plan, a process could easily produce a partisan
outcome, even if it wasn’t intended to,” said Eric McGhee, senior
fellow at the nonpartisan Public Policy Institute of California.
The AP’s analysis of partisan advantage in congressional districts
was based on a model developed by McGhee and Nick Stephanopoulos, a
law professor at Harvard University.
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