based on the decisions of some of the most important people

in politics - the map-makers that draw the electoral

boundaries.

We'll explore some examples from America's past

and its present to understand more

about the power of these election maps.

Let's start by looking at just some of the basic principles

involved.

We've got these Tiddlywinks here to help us see what

some of those problems are.

So when we're talking about election maps,

people don't normally think of it in terms of points.

But that's what we're actually visualising,

isn't it, is information about individuals and how they voted.

Exactly.

And one of the big challenges of not just election maps but maps

in general is how we take information

from individuals who voted, in this case,

and convert that into information about areas.

Now, that's something that geographers

call the modifiable aerial unit problem.

If we modify our aerial unit, which is essentially

the areas that we're going to group people into

- in this case it's these chips here

that we're going to pool together

- if we group them together in different ways,

we're going to get a different answer to the question

that we're asking.

And actually, fundamentally, there

isn't a perfect answer to this.

So we're going to keep moving stuff around all the time.

So we're going to have a look now at these imaginary voters

that we have here who have all voted

for different political parties.

And the first thing about this problem

is that there is a problem of scale.

So as you change the size of the area, you know,

the colour with the most counters changes

as you're sizing the area.

You can see that on the summary results here,

we're changing who's the overall winner simply by varying

the size of the area.

And this actually is also a function

a bit of the density of the points as well.

So it may be that in a rural area

you could get away with a very big area for our constituency

or district, but not many people live in it.

If you did the same thing in an urban area,

you're going to be exacerbating potential issues in a way

that you wouldn't be in the rural because, you know,

people are much more tightly packed.

There's much more variety and diversity in the way

that people are voting.

As these areas get bigger, we can see quite clearly -

from yellow to red to blue - it's easy to see how the area

size can completely change your view of whether an area is

affiliated to one particular political organisation

or another.

So what we're going to do now is take all of these counters

back off the screen and just go focus down

to four imaginary voters.

So if we take this fictitious voting area here - so

we've got an imaginary area that we're

going to populate with four voters

- just four voters to keep this nice and simple.

And we want to divide this area just into two summary areas.

Where we draw the line makes a big difference.

If we draw the line width ways across the screen,

we've got a perfect balance of two in each area.

Because people aren't dispersed evenly,

if we just change the orientation of this line

and divide it the other way, we end up with 1 and 3.

So we've changed the number of voters

in each area just based on where the line's being drawn.

That's okay when everybody's voting yellow.

The issue starts when we take two of these yellows

away and say, well, actually, they're voting red.

And now what happens is that the line makes a big difference

to the outcome of our imaginary election,

even just with four voters.

With the line oriented this way, this side

is 100 per cent yellow, and over here it's two thirds red,

one third yellow.

What's going to happen when we change our line?

We've actually completely reversed the scenario.

This zone out on the left-hand side is now 100 per cent red,

and this zone over here is now two-thirds yellow and one-third

red.

So this is an example of the zoning problem.

And the reason why this is so significant when

we're thinking about social characteristics

like how people vote - people with similar characteristics

tend to live closer together.

But what we're actually dealing with here

in the kind of real world examples

is how people with similar views tend to cluster together.

You hear this all the time about target seats

and so on in elections.

That's important, because then it

makes it much more significant where these lines get drawn.

That's something that the Electoral Reform

Society looked at recently.

They produced a really interesting animation of this.

Just by rotating the zones, you can change completely

the outcome of the winner in each of the zones.

And this is starting to look more like a real world

example now here.

As you say, people tend to live closer to other groups.

So we can see patterns - kind of spatial patterns

- in the layout of the voters, but they may not always

be reflected in the eventual outcome.

No, exactly.

So far, we have been more or less randomly

rotating the geometry.

Where this gets really interesting

is when someone actually has control

of where to put our voting boundaries, our election

boundaries.

And that's something that's particularly

associated with the US because of the way

that the districting system works in the US.

So in the US, this isn't a new thing.

This is Elbridge Gerry.

He was a founding father but also initiated

a whole new genre of political manipulation

with what he did with voting boundaries.

He was organising the Massachusetts voting

boundaries, and he did something fairly unusual

which produced a map that the local newspaper satirised.

Can you explain what's going on here, James?

I suppose it's brilliant in the context of ensuring the result

would go his way - was to realise that if he created

a district that consolidated the power of his particular party

by ensuring that everyone who votes for him are in the same

district and then those in districts where maybe there are

a greater variety of voting intentions -

some people may go one way or the other -

if he puts all the people that support him in the same area,

he will secure victory.

And the strange effect of doing this, of course,

is that you end up with very oddly shaped areas

as he tries to contort the map to fit his means.

And in this case, the cartoonist said

it looked like a fictional mythical creature -

a salamander.

And that's why we end up with the phrase, gerrymander

- as in gerrymandering, which is the word

we use to refer to when people are manipulating election

districts in this way.

So I guess people might be surprised

when they see that that was 200 years ago

that that might have been something

that was nipped in the bud.

But we can see examples of this still all

over the US electoral map here.

We've got a map of the US here where

we're going to pick up on maybe five of the very evocative

names for some of these areas.

One of my favourites here is The Duck,

which is Ohio's 4th congressional district -

which obviously just looks like a duck.

It's a really peculiar shape.

Even more odd, in some ways, is this Snake by the Lake,

as it's known, because that stretches from Toledo

all the way over to Cleveland.

It's actually much narrower than this, because most of this area

is actually Lake Erie, and there really

is just a very thin sliver of land going

all this way across Ohio here.

If we pan out over towards the East Coast,

we've got a couple of really interesting ones.

This one is Goofy kicking Donald Duck, which is in Pennsylvania.

And you can see these areas are barely touching each other.

It looks like two completely different areas.

Exactly.

And the strategy here is - just imagine on the map

- go back to the counters we had on the screen

at the beginning of this.

They're just trying to draw a line without breaking it around

the counters of the colour that represent their particular

party.

Okay.

And then just south of this fantastic one is probably

my favourite name of the lot, I think,

the Broken Winged Pterodactyl of Baltimore,

which is Maryland's 3rd congressional district,

I believe.

The thing that's really odd about all of these examples

is they have such a long perimeter given

the overall area.

They're so windy, just like with Gerry's original example.

From a geographer's perspective, what we really love

is very compact areas.

So squares or circles would be the ideal,

but, of course, the world is much more complicated

than that, and so you get oddly-shaped areas.

But these are just incredibly hard to justify.

They just look completely unnatural

from a social perspective.

And really the only justification is they're trying

to maximise their voter share in this particular district.

The people responsible for delineating these boundaries

is the governing state legislature.

So if, for example, a Republican state has got a responsibility

to redraw the boundaries, it's much more likely

that you're going to see boundaries

that reflect a better potential outcome

for the incumbent party.

This is where, actually, politics kind of overlaps

with the independence of statistical authority

and things like that.

In the US, they've got a census coming up.

Knowing where people are is actually an important basis

for where you can draw these boundaries

and how many boundaries you get.

And you end up with this kind of tit-for-tat thing going

on where if they manage to beat this and change party

representing the area, the boundaries would

be redrawn again.

There is one word of caution with this, though, isn't there,

because we've already seen that regular shapes might not

be the best way of making sure that we're

capturing appropriate community characteristics.

And actually, if we zoom back out again

and go over to Illinois, there's a very famous example

in Chicago called The Earmuffs, which is, again,

on the face of it, this looks like another one

of those really oddly-shaped gerrymandered districts.

This one's a bit different, though, because this one

was the result of a federal instruction to give Hispanics

greater voting representation.

And so these two areas here on The Earmuffs

are both majority Hispanic areas, which, in isolation,

if these were split apart, probably

would suffer from the symptoms of our counters earlier.

I mean, one of the interesting differences between the US

and, say, the UK, is that the US, because of the way

the population spread across the US,

it was starting from scratch in many ways

drawing these boundaries and planning cities and so on.

In a country like the UK, we've had 1,000-plus years