GEOFF BENNETT: Nearly 35 million Americans will vote in congressional districts that were redrawn ahead of this year's midterms following partisan battles over political maps.

As the nation marks its 250th anniversary, our Judy Woodruff explores the origins of gerrymandering and why this centuries-old practice remains one of the most powerful tools in American politics.

It's part of her ongoing series Crossroads: America at 250.

JUDY WOODRUFF: The items on these cards are rare political artifact, protected by Library of Congress curators who carefully brought them out of their Archives.

WOMAN: What you're seeing today is a copy of the original Boston Gazette, where you see the actual first appearance of the gerrymander cartoon.

JUDY WOODRUFF: What year was this?

WOMAN: And this was March 26, 1812.

JUDY WOODRUFF: 1812.

At the time, Massachusetts Governor Elbridge Gerry had approved redrawn districts in the state in a bid to keep his party in power.

As the story goes, a newspaper editor saw a salamander in the map's outline, combined it with Gerry's name, and a new word entered the American political vocabulary, gerrymandering, or, as it became, gerrymandering.

NICK SEABROOK, University of North Florida: This is, I would argue, probably the very first example of a viral meme in American politics.

So it spread around The Federalist newspapers in the New England era, and then over the subsequent year it was reprinted in almost 100 newspapers across the country.

WOMAN: It's depicted as this mythical salamander beast.

JUDY WOODRUFF: The library also has the wood blocks used to print this piece of history.

More than two centuries later, gerrymandering is flourishing and playing out in state after state.

The latest round of mid-decade redistricting intensified last year when, at President Trump's request, Texas redrew its congressional maps to try to add five Republican seats.

After that, other states entered the fight.

California Governor Gavin Newsom called a special election to redistrict and pick up more Democratic seats.

GOV.

GAVIN NEWSOM (D-CA): They want to rig these elections and they want the power that gerrymandering provides, because they know what Donald Trump knows.

He's going to lose the midterms.

DONALD TRUMP, President of the United States: The Democrats, or as I call, the Dumocrats, because they are dumb in so many ways, they have redistricted for years, and now we took our shot, and it looks like we're going to pick up a lot of seats.

NICK SEABROOK: The motive for gerrymandering is almost always power.

It's a product of polarization, of Democrats and Republicans not just disagreeing, but actively hating each other.

Negative partisanship is such an incredibly strong force in our politics today.

JUDY WOODRUFF: Nick Seabrook is the author of "One Person, One Vote: A Surprising History of Gerrymandering in America."

He says the practice of manipulating district lines to protect political power is actually older than Gerry.

It began with George Burrington, a colonial governor of North Carolina in the 1730s.

NICK SEABROOK: His attempt to manipulate the districts of the colonial assembly was motivated by a desire to try and prevent the columnists themselves, who elected the lower house of that legislature, from pushing back on the taxes and fees that his administration was charging to try and expand the footprint of the North Carolina colony.

JUDY WOODRUFF: So he had a motive, or motives, for what he was trying to do.

NICK SEABROOK: He did, yes.

JUDY WOODRUFF: Does that qualify as redistricting or gerrymandering as we know it today, manipulating?

NICK SEABROOK: I would say this was certainly gerrymandering because there was no -- there was no legal obligation for him to make any changes to these districts.

He approached it purely as an exercise in maximizing his own political power.

JUDY WOODRUFF: This year, that maximizing of political power has ended up with mid-decade redistricting in nine states, Texas, California, Utah, Ohio, Tennessee, Louisiana, Alabama, Florida, and North Carolina.

From the colonial days of George Burrington to today, North Carolina has been one of the most gerrymandered states in the country.

When congressional maps are redrawn, they sometimes split communities right down the middle.

That's the case in the small town here of Sharpsburg, North Carolina, where three counties come together.

I'm standing at the northernmost edge of the Third Congressional District, but if I take just a few steps across these railroad tracks, you will see I have moved into the First Congressional District.

When Republican state lawmakers redrew these and other lines last year, they said they were trying to pick up one more Republican seat in Congress.

Several counties shifted from one district to another, changing the demographics of both, spreading out eligible Black voters and weakening their electoral power.

The city of Wilson is one of the communities plucked out of the First District and placed in the Third.

For the 50,000 people who live here, the question is, what will the switch mean for their voice in Congress?

Castonoble Hooks has lived in Wilson his entire life.

CASTONOBLE HOOKS, Wilson, North Carolina, Resident: This is a traditional Black area, where most of the original Black residents still live.

JUDY WOODRUFF: He remembers the days of Jim Crow laws, when the town was segregated.

CASTANOBLE HOOKS: What disenfranchisement taught us is that if you're not a part of the political process, you are left behind.

JUDY WOODRUFF: Today, Hooks is a regular fixture at the senior center where he teaches chess and encourages his neighbors to vote.

CASTONOBLE HOOKS: I voted in every election since I have been 18.

Does my vote count?

I hope it did.

But I'm going to keep voting.

JUDY WOODRUFF: Do you think this new district that you're in, this newly drawn district, represents Wilson, the way it's drawn.

CASTONOBLE HOOKS: No, it dilutes our vote.

It dilutes the Black vote.

It puts us with a large number of white people, so much so that our vote is -- if all of us vote one way, it probably won't affect the outcome.

BRITTANY HAMM, Wilson, North Carolina, Resident: And it feels like our votes are kind of being taken away.

It feels like our voice isn't heard, and that's what disconnects and make people not even want to vote.

JUDY WOODRUFF: Thirty-six-year-old Brittany Hamm was born and raised in Wilson.

She's raising three kids here and works to educate people about the political process.

RAYMOND SMITH JR.

(D), North Carolina Congressional Candidate: What we have before us, we have a Congress right now with no backbone.

(APPLAUSE) JUDY WOODRUFF: She's a community organizer and active in local politics.

BRITTANY HAMM: As constituents or voters, we're supposed to choose who represents us.

When they redistrict or they redraw these lines, they're picking the voters, instead of the voters picking them.

And that's not fair to us, because Wilson didn't move, the needs didn't change, but yet you're moving us.

NICK SEABROOK: It's an unfortunate situation where we, as the people, we as citizens can find ourselves cut out of that fundamental democratic role of choosing our representatives in government.

JUDY WOODRUFF: Nick Seabrook says the consequences go beyond any one community.

They go to the heart of democracy itself.

NICK SEABROOK: Because elections are our only voice, there's no way that we can that we can fix that when the election itself has been -- has been rigged against us.

JUDY WOODRUFF: Is it consistent with democracy?

NICK SEABROOK: I don't believe that it is.

I don't believe that you can call yourself a healthy democracy when gerrymandering is as rampant as it is in the United States today.

JUDY WOODRUFF: Given all this, where does it leave the average voter, the ordinary voter?

NICK SEABROOK: It leaves the average voter in a situation where they can never be sure in their individual districts, in their individual state whether the deck has been stacked ahead of time.

I argue that it's not sufficient to place constraints on redistricting to prevent gerrymandering.

The only way to effectively fix this is to just take that power away from the elected branches of government, because you leave the foxes in charge of the henhouse.

It doesn't matter how many sternly worded letters you send them telling them not to eat the chickens.

That's what it's in their nature to do.

JUDY WOODRUFF: For the "PBS News Hour," I'm Judy Woodruff in Wilson, North Carolina.