1775年，华盛顿打响了反抗英国殖民者的第一枪，经过8年抗战，1783年，英国承认了美国的独立，并把密西西比河以东的殖民地割让给了美国，这大概就是美国领土扩张的“第一桶金”吧。
1791年，美国将佛蒙特地区并入，不过可以忽略不计。到了1803年，美国花了1500万美元从法国手中买下了名叫“路易斯安那”的殖民地，领土面积增加了214万平方公里。1818年，美国由跟英国签了条约，把路易斯安那背面，北纬49度以南一块不算太大的地区并入版图。
1819年，西班牙国力衰落，每况愈下。于是美国看准时机，从西班牙手中“购买了”佛罗里达地区，领土增加了约不到20万平方公里。
1836年，美国策动墨西哥的得克萨斯省从墨西哥独立，成立了“孤星共和国”，其领土范围包括现今美国的得克萨斯州以及新墨西哥州、科罗拉多州、怀俄明州、奥克拉荷马州、堪萨斯州的部分地区。1845年，“孤心共和国”通过“决议”加入美利坚合众国，美国领土就此增加了约80万平方公里。
1846年，美国以战争威胁，迫使英国承认以北纬49度为美国和加拿大的国土分界线，美国就此获得了近100万平方公里领土。
1846年，因为孤星共和国的独立以及后续领土划分问题，美国与墨西哥就开战了。由于墨西哥国力较差、对北方领土的控制力不足，军队战斗力也不够，导致在1848年的战争中败给了美国，连首都墨西哥城都被美军攻占。无奈之下，墨西哥和美国签订“城下之盟”，将近230万平方公里的领土割让给了美国。如今名满全球的洛杉矶、硅谷和拉斯维加斯等著名城市，就是这个时候成了美国的领土。1853年，美国又从墨西哥“购买”了一小块领土。
1867年，美国用了720万美元从沙皇俄国手里买了阿拉斯加。当时很多人都不理解美国的这个决定，但现在看来，这确实是笔划算的买卖，而俄罗斯至今还为这笔买卖后悔不已。多年后，建造一艘要沉没的泰坦尼克号花费还需要750万美元呢。
1867年10月18日，面积171万平方公里的阿拉斯加正式成为了美国领土。
1795年，由欧胡岛、茂夷岛、莫洛凯岛、拉奈岛、夏威夷等岛屿的小型独立部落统一成立了夏威夷王国。美国本来也承认夏威夷王国为主权独立国家，但后来就不认了。
1893年1月17日，夏威夷的美国移民在美国政府的支持下发动政变，软禁了夏威夷女王，成立夏威夷共和国，美国从此在实际上控制了夏威夷。
1898年，夏威夷共和国宣布取消自己的独立国家地位，并入美国，美国领土就此增加了1.67万平方公里。1959年，夏威夷正式成为美国的一个州，美国终于收集齐了自己国旗上的五十颗星。
就此二战之后，美国的领土扩张就此告一段落。现在美国领土面积为963万平方公里，共有五十个州、一个特区以及若干海外领地。
各位看官是不是以为美国就这些领土，那就大错特错了。
1898年美国西班牙进行了战争，西班牙战败把波多黎各割让给了美国，政治地位是美国控制的“自由联邦”，面积约为1.4万平方公里。
在第二次世界大战激战正酣的1944年7月，美国占领了关岛。第二次世界战争结束后的1950年，美国宣布关岛为其“未合并的领土”，面积为549平方公里。
除此之外，美国在太平洋和大西洋，包括加勒比海也有不少群岛领土，但是不是成建制的领土，如北马里亚纳群岛（塞班岛，天宁岛）、美属维尔京群岛、美属萨摩亚、贝克岛、约翰斯顿环礁和中途岛等。
西进运动（Westward Movement）是指美国东部居民向西部地区迁移和进行开发的群众性运动，始于18世纪末，终于19世纪末20世纪初。运动大大促进了美国经济的发展，但是，随着西进运动的进行，大批印第安人遭到屠杀，幸存者被强行赶到更为荒凉的“保留地”。印第安人被迫迁徙之路也被称为印第安人的“血泪之路”。
美国独立后掀起了长达一个世纪的西进运动，西进过程中，大批移民出于不同的原因迁往西部，客观上缓和了资产阶级内部矛盾，扩大了国内市场，破坏了自由州与蓄奴州的平衡，为南北战争的胜利打下基础。从某种意义上说，没有西进运动，就没有后来美国在资本主义世界举足轻重的地位。正因为如此，有的学者在研究西进运动时，对它的积极作用大肆赞扬，而对另一方面却轻描淡写，那就是对土著印第安人的野蛮屠杀。
西进运动是美国拓宽疆土，吞并土地的一种侵略行为，它开发了如今的美国西部地区，消灭了众多印第安文明，当时只是东边的殖民地地区，需要大量的土地，当地已经满足不了人口和经济发展的需要，于是把目光投向了西部，当时西部的土地都是印第安部落的。有一帮先驱者向西部探索，并和印第安部落建立了良好的关系，一直行进到太平洋，就是现在墨西哥一带。后来大量人包括政府和军队涌入西部，通过劫掠、诱导、欺骗、屠杀印第安人，并开发西部地区。
A Brief Introduction
Westward movement in America carried settlers across America, from the Atlantic Ocean to the Pacific Ocean. The westward movement began in the early 1600's with European settlements along the Atlantic Coast of North America. It continued until the late 1800's. An abundance of land and other natural resources lured America's pioneers westward.
Fur traders, cattle ranchers, farmers, and miners led the push to the west. Merchants and other business people followed. These hard-working men and women faced great dangers, endured severe hardships, and suffered loneliness and boredom in the hope of making a better life for themselves and their children. Some of them looked to the west for wealth or adventure. Others sought to improve their social position or increase their political power. The pioneers struggled westward across hills, mountains, and prairies on foot and on horseback. Some floated through the Erie Canal on barges or traveled down rivers on flatboats and steamboats. Others crossed the rugged wilderness in covered wagons.
The First Period
The first period (from the War of Independence to the Civil War) --- the mainly agriculture-based initial development period
The federal government took a number of political measures to promote the westward movement in the land and agricultural development, mainly in the following areas:
(A) land policy（土地政策）
Firstly, the U.S. government issued the procedures and requirements in the statehood in the West.
Secondly, the U.S. government enacted the policy to ensure the residents’ access to the land.
In 1785 “Land Ordinance” (土地条例) determined the state-owned land for sale to the immigrants - 国有土地向移民出售
From 1802 to 1832a number of “Relief Act” delayed the period of unpaid confiscation of land - 延缓未付土地被没收的期限 (poor farmers got the land)
In 1832Jackson administration allowed farmers to occupy the land, and they could buy the land they have cultivated and improved with the lowest price .
In 1862Lincoln Government the “Homestead Act (宅地法)” required that citizens of 21 years old could acquire at most 160 acres of lands, as long as they could afford 10 dollars and farm it for 5 years. 年满21岁的公民从1863年1月1日起，只要付10美元的费用，就有权取得160英亩或以下的土地，耕种5年后，土地就归个人所有
(B) immigration policy（移民政策）
American Land Act in 1787 provided some principles for establishment of a new state, and the third part in it also made provision for the rights of citizens, particularly people could move westward freely. It greatly promoted the influx of American immigration to the west. Since then, the mass of the large-scale westward movement flourished, and the immigrants provided sufficient labor.
(C) infrastructural development policies（基础设施发展政策）
Westward Movement in the United States attached great importance to infrastructure, in particular paid great attention to railways, highways, waterways and other transportation infrastructure. In the railway construction the U.S. Government has taken a "much more railroads more benefit policy"（多修铁路多得益政策）. In road construction, an important U.S. government policy was to encourage private investment.To address the lack of highway construction funds, toll roads (收费公路) became the first priority in the development of the business. With the invention of the steam engine and the use of the ship, the U.S. government stepped up the construction of water transport, and became the world's most developed country in canal in the 1940s.
The Second Period
The second period refers to the time between the Civil War and World War II, and it was mainly based on industry. By the end of the Civil War, especially after the reconstruction of the South, the economy grew rapidly in South, and there emerged a relatively stable political situation. At the same time, the second industrial revolution was rapidly rising, and the United States began the transformation from an agricultural country to an industrial one. Government adopted a more favorable and open policy to promote the westward movement.
(1) The U.S. government adopted preferential policies to attract foreign investment in infrastructure, and took more favorable subsidies to attract private investment to build canals and railways.
(2) It adopted an open policy to attract outstanding foreign labor. Law of wood stone (Laws enacted ) in Northern Europe, Eastern Europe, Southern Europe, and many other countries there appeared "American fever", the dream of hundreds of people who traveled tirelessly across the oceans, and were looking forward to the American "Western Garden." In the period of 1861 -1914 more than 27 million foreign immigrants settled in the United States with certain finance and technique, and made an indelible (永久的/不可磨灭的) contribution .
(3) The us government put more emphasis on environmental protection and the use of technology.
- 1877 "Sandy Act"
- 1894 "Carey Act"
(4) The government paid attention to the balanced development of industry and mining in the east and the west.
The Third Period
After the end of World War II, the computer network technology, nuclear technology, biotechnology and space technology first occurred in the United States as an important symbol of the third technological revolution. During this period the U.S. government's major policies were:
v1. the use of risk-investment mechanism, and establishment of high-tech parks.利用风险投资机制，建立高科技园
Silicon Valley high-tech parks in the 60's in San Jose, California
v2. the use of regional economic management policies to promote development of the west
- 1961 Redevelopment Area Law 地区再开发法
- 1965 Law of “Public Works and Economic Development",
"Appalachian Regional Development Act" 《阿巴拉契亚区域开发法》
- 1977 Community Reinvestment Act 社区再投资法
v3. the use of market forces, to promote the economic development of backward areas.
