Before Louisiana there was Detroit...
Acquiring Louisiana – A royal story that began in “Nouvelle France” (later named Quebec).
When King Louis XIV, decided to expand the Kingdom of France beyond the oceans, he sent an exploration mission to create Nouvelle France. Later, the explorers launched a journey in canoe to the unknown traveling south on the St Lawrence River through the wild, inhabited by ‘painted’ savages. They settled their camp as they arrived at a crossing of three rivers naming it: Camps des Trois Rivieres.
Its proximity to waterways was ideal to build a trade post bearing a name that was quickly shortened to “Des Trois”.
A more Anglo-Saxon pronunciation later converted the name to Detroit.
Who founded the city of Detroit...
Antoine de la Mothe – a French aristocrat and 
explorer whose name would be engraved on the hood of an American car was also known as the Count of Cadillac, founder of Detroit. General Motors would name their best car after him to honor the founder of their city.
Why was the Louisiana territory so large...
Traveling along the Mississippi river for months by canoe and horseback, the French missionaries were dedicated to acquire new land for their king by planting the royal flag of France as close as the horizon whilst shouting the words: “In the name of Louis, we acquire this land as far as the eye can see”.
And there was Louisiana.
Its size was 1/3 of today’s United States and consisted of 15 states of today’s US.
Why did Napoleon sell Louisiana to the Americans....
Fortunately for the US, Napoleon’s eyes were turned toward Europe and his desperate need to fund an obsessive war against Russia and England.
The emperor wanted to keep it but knew it was too far and too large to defend.
He sold the port of New Orleans for $5 million and then offered the entire territory of Louisiana in 1803 for a bare $15 million ($0.03 per acre!).
Food for thoughts....
The Gold Rush period sparked a new wave of trade, mapping a new commerce routes between the West and East coast, which happened to cross the Louisiana territory. With most waterway trades of the US Colonies taking place from the port of New Orleans, had Napoleon chosen to keep it, the US would have been forced to declare war on France to acquire it.
In fact, President Jefferson wrote a secret coded note to Ambassador Livingston stipulating that if France chose not to sell Louisiana, to prepare for a possible alliance with….England to acquire New Orleans by force.
An ironic, yet possible scenario despite the considerable role France played aiding the US defeat the British.
However, the suspense ended with the sale of the territory, which Napoleon ceded to the US at a bargain price to seal an iron alliance with the newly founded US Republic. Against England.
English 
Français