The United States of America was formed after thirteen British colonies in North America declared independence from the British Empire on July 4, 1776. In the Lee Resolution, passed by the Second Continental Congress two days prior, the colonies resolved that they were free and independent states. The union was formalized in the Articles of Confederation, which came into force on March 1, 1781, after being ratified by all 13 states. Their independence was recognized by Great Britain in the Treaty of Paris of 1783, which concluded the American Revolutionary War. This effectively doubled the size of the colonies, now able to stretch west past the Proclamation Line to the Mississippi River. This land was organized into territories and then states, though there remained some conflict with the sea-to-sea grants claimed by some of the original colonies. In time, these grants were ceded to the federal government.
The first great expansion of the country came with the Louisiana Purchase of 1803, which doubled the country's territory, although the southeastern border with Spanish Florida was the subject of much dispute until it and Spanish claims to the Oregon Country were ceded to the US in 1821. The Oregon Country gave the United States access to the Pacific Ocean, though it was shared for a time with the United Kingdom. The annexation of the Republic of Texas in 1845 led directly to the Mexican–American War, after which the victorious United States obtained the northern half of Mexico's territory, including what was quickly made the state of California. However, as the development of the country moved west, the question of slavery became more important, with vigorous debate over whether the new territories would allow slavery and events such as the Missouri Compromise and Bleeding Kansas. This came to a head in 1860 and 1861, when the governments of the southern states proclaimed their secession from the country and formed the Confederate States of America.
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The economic history of the United States is about characteristics of and important developments in the economy of the U.S., from the colonial era to the present. The emphasis is on productivity and economic performance and how the economy was affected by new technologies, the change of size in economic sectors and the effects of legislation and government policy. Prior to the European colonial conquest of North America, there were indigenous communities with varied economic structures.
In the context of the United States, secession primarily refers to the voluntary withdrawal of one or more states from the Union that constitutes the United States; but may loosely refer to leaving a state or territory to form a separate territory or new state, or to the severing of an area from a city or county within a state. Advocates for secession are called disunionists by their contemporaries in various historical documents.
The District of Louisiana, or Louisiana District, was an official and temporary United States government designation for the portion of the Louisiana Purchase that had not been organized into the Territory of Orleans or "Orleans Territory" (the portion of the Louisiana Purchase south of the 33rd parallel, which is now the Arkansas–Louisiana state line). The district officially existed from March 10, 1804, until July 4, 1805, when it was incorporated as the Louisiana Territory.
Simulated present and future air quality is compared for the years 2006-2010 and 2048-2052 over the contiguous United States (CONUS) using the Community Multi-scale Air Quality (CMAQ) model. Regionally downscaled present and future climate results are deve ...
Severe thunderstorms can have devastating impacts. Concurrently high values of convective available potential energy (CAPE) and storm relative helicity (SRH) are known to be conducive to severe weather, so high values of PROD - (CAPE)(1/2) x SRH have been ...
AMER METEOROLOGICAL SOC2021
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Many sensitive ecosystems in areas protected for biodiversity conservation in the United States suffer from exposure to excess reactive nitrogen (Nr) released by fossil fuel combustion and agricultural practices and deposited onto the land surface and wate ...