The document discusses several topics related to 19th century history:
1) The American states struggled to build nations and societies after gaining independence from European powers in the late 18th/early 19th century. The US expanded rapidly westward and absorbed much of North America by mid-century.
2) The Little Ice Age occurred between the 16th-19th centuries and led to expanded glaciation and cooler global temperatures. This impacted human health in Europe through malnutrition and disease spread.
3) The US purchased the Louisiana Territory from France in 1803, doubling the size of the country and encompassing land that makes up 14 current US states and two Canadian provinces.