The United States customary system (also called American system or, sometimes, "English units") is the most commonly used system of measurement in the United States.
A republic is the name for such a system. The United States is a republic.
The United States is a free enterprise system.
United States Capitol subway system was created in 1909.
The United States of America
The United States does not use the metric system.
Adversarial system
The economic system of the United States is a capitalistic market economy, based primarily on free enterprise.
In the United States, the Head of the Armed Forces is called the Commander-in-Chief and this position is held by the President of the United States. The president is a civilian political officeholder. So the United States should be understood as having a military system that is under civilian control.
United States
One can purchase a professional karaoke system from within the United States from many places. The most common places to purchase a professional karaoke system in the United States are ToysRus, AceKaraoke, and eBay.
The Coinage Act of established the United States coinage system. It was also commonly known as the Mint Act.