Why is Tennessee nicknamed Volunteer State?

Tennessee-"parallel slash state"; Nicknames for the fifty states of the United States.

The nicknames of States can be roughly divided into the following categories:

Another name that reflects historical events. Pennsylvania-"pillar state" (or cornerstone state); Colorado, the "Centennial State", joined the Union on the centenary of American independence. Virginia-"presidential state", because four of the first five American presidents were born in this state. Oklahoma-"First-come-first-served state" refers to moving to the west in the early years before the official approval of the US government, and obtaining the possession of local land, which made the residents of Oklahoma gain a lot. Louisiana-"the descendant state of French immigrants", because the first French immigrants settled in this state. Kansas-"Guerrilla State", there were many guerrillas who supported the abolition of slavery during the American Civil War.

Another name that reflects the economic characteristics or specialties of the state. Alabama-"Cotton State"; Arkansas-"Bear State"; California-"Golden State"; Idaho-"Jewelry State"; Kentucky-"the ranch state"; Maine-"Timber State"; Michigan-"Wolverine State"; Minnesota-"the state of Sophora japonica"; Montana-"rich mine state"; Nebraska-the "Elk State"; Nevada-"Silver State"; Connecticut-"Nutmeg State"; Delaware-"Gem State"; Georgia-"Cookie State"; New Hampshire-"Granite State"; North Carolina-"Pine Gum State"; North Dakota-"Golden Winged Woodpecker Tail State"; Ohio-"Buckeye State"; Oregon-"the scarlet state of the sea"; Rhode Island-"Little Rhode Island Red State", this state is rich in red Rhode Island red chickens; South Carolina-Palm Tree State; South Dakota-"Little Wolf State"; Wisconsin-"Irrigation State".

Another name that reflects the characteristics of local residents. Missouri-"Show me this state". Residents in this state are skeptical and generally don't believe what others say easily. Their creed is: hearing is empty, seeing is believing. "Let me see" is often talked about, so it becomes another name for Missouri.

Another name for geographical location, topographical features and population density. Florida-the "swamp state"; Illinois-"Prairie State"; Massachusetts-"Bay State"; Mississippi-Hekou State, named after the Mississippi River, the third largest river in the world, flows into the Gulf of Mexico through Honshu; Tennessee-"parallel slash state"; Vermont-"Green Mountain State"; West Virginia-"Narrow State"; Texas-"a sparsely populated state"; Utah-"densely populated state".

Another name related to the sun. New Mexico-"Sunshine State"; Alaska-"Midnight Sun State"; Arizona-"Sunset State".

The nicknames of other states also have certain characteristics. New york-"the state of empire"; Wyoming-"Equal State"; Washington State-"Evergreen State"; New Jersey-"Garden State"; Indiana-"Country State"; Maryland-"a state with a long history"; Hawaii-"Aizhou" (Hawaiian means "love"); Iowa-"Hawkeye State".