Conex vs. Shipping Container: Same Box? The U.S. Army History of "CONEX"

If you've heard someone call a shipping container a "conex", you might wonder whether they mean something different. They don't. Today, "conex" and "shipping container" mean the same thing, and the word has a history that goes back to the U.S. Army.

Here's where the name came from, how those early boxes led to the containers we use today, and what to know if you're shopping for conex shipping containers for sale.

The short answer

A conex is a shipping container. You'll hear "conex" most from contractors, farmers, military veterans and people in parts of the West and South, while "shipping container", "cargo container" and "storage container" are more common elsewhere. They all describe the same steel box.

Where "CONEX" came from

CONEX stood for Container Express, the U.S. Army's system of reusable steel shipping boxes introduced in the early 1950s. The Army needed a better way to move supplies overseas. Loading loose crates and sacks onto ships by hand was slow, and goods were lost, damaged or stolen along the way.

The Army's answer was a sturdy, lockable steel box about 8½ feet long that could be packed at a depot, shipped, and opened only at its destination. CONEX units were used heavily during the Korean and Vietnam wars, and their success helped show what standardized containers could do.

From Army box to global standard

Commercial container shipping took off in the mid-1950s, when trucking entrepreneur Malcom McLean shipped loaded trailer boxes on a converted tanker in 1956. His idea was simple: instead of unloading and reloading cargo at every step, move the whole box from truck to ship to truck.

Over the following years, the industry agreed on standard sizes and fittings so containers could be stacked, lifted and locked together anywhere in the world. That's why today's containers come in standard lengths, such as 20ft and 40ft, are 8 feet wide, and have the same corner castings at every corner.

The original CONEX box was smaller than today's containers, but the name stuck, and "conex" became a common word for any shipping container.

Why the humble box mattered so much

Standard containers changed how the world moves goods. Before them, ships could spend days in port while workers loaded and unloaded loose cargo by hand. With containers, a ship can be loaded and unloaded by crane in a fraction of the time, and the same box can travel by ship, train and truck without being opened.

That made shipping far cheaper and more reliable, and it's a big part of why goods made on one side of the world can be sold affordably on the other. It's also why there are so many used containers in the U.S. today: more full containers arrive than leave, and the older ones are eventually retired and sold for storage.

How people use a conex box today

• On-site storage for homes, farms, businesses and job sites
• Moving and renovation storage
• Site offices, workshops and tool rooms
• Cold storage, using refrigerated containers
• Pop-up shops, bars and event booths
• Homes, cabins and studios
• Shipping goods overseas, the job they were built for

Conex, container, sea can: what people call them

Is there any difference at all?

Only in a few narrow cases:

• Military CONEX units: original Army boxes were smaller than today's 20ft and 40ft containers. You'll occasionally see old ones for sale as surplus.
• Purpose-built storage boxes: some small "conex" units, like 8ft and 10ft containers, are built for storage rather than shipping. They look and work like shipping containers.

Otherwise, a conex box for sale today is a standard shipping container.

Buying a conex today

Whatever you call it, the decisions are the same:

1. Size: 8ft, 10ft, 20ft, 40ft or 45ft.
2. Type: standard, high cube, open side, open top, refrigerated, insulated, flat rack or custom.
3. Condition: new (one-trip) or used, with grades for used units.
4. Buy, rent or rent-to-own: see conex rental.

FAQ

What does CONEX stand for?

Container Express, the U.S. Army's system of steel shipping containers introduced in the early 1950s.

Is a conex box the same as a shipping container?

Yes. Today the terms are used interchangeably.

Why do people say "conex" instead of "container"?

The Army's CONEX units were widely used, and many veterans, contractors and farmers kept using the name for any steel shipping container.

Can I still buy an original military CONEX box?

Occasionally, as surplus. They're smaller than modern containers and often older, so check their condition carefully.