Did you know there are nine different classifications of truck in the USA? They are ranked by the maximum haulage weight a truck can carry, and cover Light Trucks, Medium Trucks and Heavy Trucks. The scope of the US truck industry – and trucking itself – is massive and brings in hundreds of billions of dollars of income every year. This long-established business is one of the most important in the USA and moves most of the freight on the continent.

In this article we’re going to talk about the semi-truck. What is a semi-truck, why is called such, and what  examples are there? We’ll talk about all that and more below. It’s also worth considering the role of semi truck part companies and their suppliers, who also make up a considerable business across the USA. Let’s begin by talking about the semi-truck and its origins.

The Semi-Truck Explained 

When you see one of the big trucks on the road, or even a convoy of them, you’re most likely watching a semi-truck do its job! These are the giants of the roads of the USA, massive vehicles with incredible load-carrying capacity, super-powerful engines and many axles. The semi-truck is a Class 7 or 8 truck – the Heavy Truck categories – and some are simply colossal.

The name, semi-truck, in fact originates from the trailer rather than the powered part of the vehicle. The trailer attaches to the cab at the front; it has no wheels as this part so cannot move on its own. This is why they were named ‘semi-trailers’ as they need another component to become movable. The name stuck, and the semi-truck was born. These trucks are also known as ’18-wheelers’ thanks to that being the usual number of wheels the chassis has attached.

Why are 18 wheels necessary? The Class 7 and 8 trucks can carry a load weighing as much as 80,000lbs. To enable this to be safe, the weight is spread across the 18 wheels. Most of the trucks could pull more weight, but 80,000lbs is the maximum permitted. So, to be classed as a semi, the truck needs to pull a semi-trailer, to be a Class 7 or 8 vehicle, and to have 18 wheels.

Why Semi-Trucks are Important 

The trucking industry in the USA is a massive one, not just in terms of money but also in the amount of freight it moves. Trucks are used to move everything from machinery to food, and there are some 1.9million heavy trucks on the roads of the USA. This is because road freight accounts for most of the freight moved in the USA – 70% in fact. The reasons for this are the direct nature of road transport – it can be door to door in many cases – compared to rail and air freight, and the greater cost of the latter.

As semi-trucks have the biggest load capacity, they are the most important carriers on American roads. They take goods across the country, up and down, and to all states every day, continuously. Without the semi-truck the US would not be able to keep things up to speed. So, give a thought to the dedicated drivers of those massive rigs you see on the roads, as they are driving for you, day after day.

Semi-trucks are also built to be rugged and to deal with the varied terrain and weather conditions experienced across the USA. They are the tough guys of the road, able to do thousands of miles a year. Be aware that a long-haul truck will cover some 100,000 miles each year. The semi-truck may just be the most important vehicle on the roads of the USA, so where do they come from?

The Major Players in the Semi-Truck Market

The major truck manufacturers of the USA may not be the brands you are thinking of. For example, Ford may have the most successful truck range of all with the F-Series, but it is not a player in the Class 7 and 8 semi-truck markets. Neither is GM, which may surprise a lot of people. However, the Daimler Group is the market leader with the famous Freightliner range of semi-trucks and by building almost 200,000 models a year takes around 40% of the market.

Next in line come the Kenworth and Peterbilt brands, which are both part of the same company and between them have around 30% of the semi-truck market. The remainder of the market share is split between International, a long-established American brand, and the Volvo group – including Mack Trucks – as well as a several smaller manufacturers.

That so many brands are involved in the semi-truck manufacturing sector is testament to the importance of this type of vehicle in keeping America fully stocked.


There’s no doubt that the trucking industry is a vital part of the US economy, and now we hope you have some understanding of the part played by the millions of semi-trucks that criss-cross the USA day after day. These massive trucks are the true wonders of the vehicle world, with untold power from huge engines, and they keep the nation running.

In fact, the history of trucking makes an interesting subject as it effectively follows the development of the USA as the mighty nation it now is, so if you’re interested check out that link for more information. So our final words have to be – keep on truckin’!