Transportation regulation is primarily designed to ensure the safety of passengers and goods. It does this by setting standards for vehicles, drivers, and infrastructure, and by enforcing those standards.

The Department of Transportation (DOT) is the federal agency responsible for regulating transportation in the United States. The DOT oversees a number of agencies, including the FAA, FHWA, FRA, and NHTSA.

The Federal Aviation Administration (FAA) is responsible for regulating the safety of aircraft and airports. It does this by setting standards for aircraft design, construction, and operation, and by enforcing those standards.

The Federal Highway Administration (FHWA) is responsible for regulating the safety of highways and bridges. It does this by setting standards for highway design, construction, and maintenance, and by enforcing those standards.

The Federal Railroad Administration (FRA) is responsible for regulating the safety of railroads and trains. It does this by setting standards for railroad track, locomotives, and cars, and by enforcing those standards.

The National Highway Traffic Safety Administration (NHTSA) is responsible for regulating the safety of motor vehicles and traffic. It does this by setting standards for vehicle design, construction, and performance, and by enforcing those standards.

Trucking is the primary mode of transportation for moving goods in the United States. In 2020, trucks accounted for 72% of all freight tonnage moved in the United States.

Automobiles are the primary mode of transportation for moving people in the United States. In 2020, automobiles accounted for 86% of all passenger miles traveled in the United States.

Walking is the most energy-efficient mode of transportation. It requires only about 100 calories per hour to walk at a moderate pace.

Air travel is the least energy-efficient mode of transportation. It requires about 1,000 calories per hour to fly at a typical cruising speed.

Walking is the most environmentally friendly mode of transportation. It produces no emissions and has no negative impact on the environment.

Air travel is the least environmentally friendly mode of transportation. It produces a significant amount of greenhouse gases and other pollutants, which contribute to climate change and air pollution.

Automobiles are the most congested mode of transportation in the United States. In 2020, the average American spent 54 hours in traffic congestion.

Walking is the least congested mode of transportation in the United States. It is not subject to traffic congestion, and it can be done anywhere.

The future of transportation is likely to include a combination of electric vehicles, autonomous vehicles, and hyperloop. These technologies have the potential to make transportation more efficient, sustainable, and accessible.