What if America were split apart? 

The Big One. Those three words make locals along the West Coast of North America

shudder with fear. This area is plagued by earthquakes. But hey, at least they

are ready. Unlike the middle of the continent, which is woefully unprepared for

the event that physically rips the United States in half. Megathrust earthquakes

are the largest and deadliest seismic events on Earth. They occur along fault

lines, where the edge of one plate is forced downward into the hot mantle

beneath another plate. The Cascadia subduction zone along the West Coast of

North America last caused a megathrust earthquake on January 26th, in the year

1700. And many people claim that it’s overdue for another one. The Cascadia

subduction zone is created by the Juan de Fuca oceanic plate which is moving

down into the mantle of the North American plate. It’s not a smooth movement

though, and pressure builds as the plates lock together. And builds, and builds.

Until the North American plate suddenly pops on top of the older Juan de Fuca

plate. This would trigger a megathrust earthquake, decimating the Western

coastline of the United States. But that’s not all. Somehow, the force of this

terrifying earthquake causes the thinnest part of the tectonic plate, between

California and Colorado, to snap. This is now an end of days nightmare scenario.

A crack races from California all across the United States, splitting the nation

in two. This deafening event would cause roads to crumble, houses to fall into

the giant crevice, and many deaths. Water from the Pacific and Atlantic Oceans

would rush in to fill the void, causing 3 m (10 ft) high tsunamis and flooding

along the midline of the U.S. Roads, power lines, and sewer pipes would tear

apart. Pipelines carrying crude oil would burst, adding toxic oil to the massive

floods. It would take a national effort to clean up and rebuild both the

coastline and Middle America. Hopefully, it would bring the country together.

And after all the rubble is cleared, we would begin to assess our new,

physically split nation. The rift would only be about 20 m (65 ft) wide. You’d

be able to wave to your neighbors from across the divide. The two sides would

gradually drift apart, at about 3 to 5 cm (1 to 2 in) per year. And the rift

would eventually grow and form a new ocean, but for now it’s just a canal. At

first, you would rely on ferries to shuttle people, cars, and supplies between

the two halves. Eventually, we would engineer segmented bridges that could be

elongated as the rift grows. The canal itself would be used as a quicker

shipping route between the West Coast and Europe. Middle America would develop

shipping ports, waterfronts, and beaches, which would attract tourists and new

residents. The new middle coastline would explode in population, with large

cities growing along this new transportation route. The U.S. would likely stay a

single nation for a while. It just went through a shared, tragic event, and the

rift is only 20 m (65 ft) wide, after all. But as the newly separated plates

began to move farther away, differences in culture and politics could increase.

And the possibility of the two sides politically splitting up would look more

inevitable. After many years of division, there could be a South United States

and the

The North United States. Now, the probability of the United States physically

breaking in two is very low to impossible. However, in Africa, it’s actually

happening along the East African Rift. But that’s a story for another What IF.