they dont -_-
the US does not have a Parliament it has the Congress.
Technically there isn't one. The closest segment of US government to resemble parliament is Congress.
Parliament
in all dimensions
The House of Representatives and the Senate
The people
There is no US "parliament". Parliament is the legislative body in Great Britain and in some other countries as well, but not in the United States. In the United States the legislative body is called Congress. The function of Congress is primarily to make laws governing the nation.
The difference between a parliamentary legislature and the the US legislature is primarily the separation of powers. In a parliamentary legislature, the head of the executive (Prime Minister) is also a member of parliament, whereas in the US the President cannot be a member of Congress.
They get approved by Parliament, similar to US process in Congress.
The US government reflects English parliamentary traditions because of the Bicameral Parliament, which has two house, the House of Lords and The House of Commons.
It was modeled after "British Parliament".
In the US this is known as Congress. In Australia, they make up the Federal Parliament.