The main reason why Alexis de Tocqueville traveled to the united states was to observe American democracy in action, and to take note of what worked and what didn't, as many European countries were going through democratic revolutions of their own.
Answer: No other European power had established a presence in the area.
In the early 19th century, Russia had already established some colonies in Alaska, securing its presence in America. Russia was expanding East, across Siberia, and eventually started moving south, until it reached Northern California.
Americans who were involved in the sea otter business proposed some joint hunting expeditions with Russian supervisors and Native Alaskan hunters to hunt seals along the Californian coast. These expeditions allowed the Russian parties to observe large stretches of uncolonized land. This led to the conclusion that a Russian settlement could be established in California.
African kingdoms are civilization because people live in kingdoms
Millions of people were killed despite very little European territory being gained or lost.