The Territory of New Mexico became the 48th state in 1912.
Alabama became a US State on 14 December 1819.
In 1776 The US declared unilateral independence from Great Britain
The US Congress.
Delaware.
Arkansas was declared a state of the US in 1836.
1846
The US declared independence in 1776.
No individual state is known as the lower 48. This refers to the 48 contiguous US states on the north American continent.
If the question actually means the 48 contiguous US States then it is Florida. Na'alehu Hawaii is the southernmost town in the US and Hawaii is the southernmost US State.
It varies from state to state. Click the link.
On 3 July 1890 it became the 43rd US State.
The US has never declared war on Britain during World War II; they were absolute, staunch allies.