Florida Purchase

The boundary between Louisiana and Florida had been long in dispute, Spain claiming all that territory south of the parallel of 31° and east of the Mississippi River, and the United States fixing it at the Perdido River, the present boundary between Florida and Alabama. In 1810, the people of west Florida met at Baton Rouge and declared themselves independent, and Governor Claiborne, of the Territory of Orleans, was sent by the President to take possession; in 1812 the Pearl River was made the eastern boundary of Louisiana, and the remainder of west Florida was annexed to Mississippi Territory ; in 1813 the fort and city of Mobile were taken by General Wilkinson. During this period a determination of gaining east Florida had been growing rapidly, and Congress, by acts passed in secret, in January and March, 1811, had authorized the President to take temporary possession. In 1818, during the Seminole War, being annoyed by Spanish assistance given to the Indians, Jackson raided east Florida, captured St. Marks and Pensacola, and hanged Arbuthnot and Ambrister, two British subjects who had given aid and comfort to the Indians. This demonstrated so completely that Florida was at the mercy of the United States that the Spanish minister at Washington signed a treaty, on Feb. 22, 1819, by which Spain ceded Florida, in return for the payment of claims of American citizens against Spain, amounting to $5,000,000. The ratification by Spain was not secured till 1821, Spain attempting to obtain the refusal of the United States to recognize the independence of the revolted Spanish-American colonies. The territory purchased comprised 59,268 square miles.

Republic of Texas

In 1833, Texas, then a part of the Mexican Republic, refused to remain a part of Coahuila, and on April 1 formed a Mexican State constitution of its own. The greater part of its population had emigrated from the southwestern part of the United States. On the abolishment of the State constitutions, in 1835, and the appointment of Santa Anna as dictator, Texas declared itself independent of Mexico, March 2, 1836. After a brief war, distinguished by two brutal massacres on the part of the Mexicans at Goliad and the ALAMO, Sam Houston, the Texan commander, with 700 men, met Santa Anna, the Mexican President, with 5,000 men, at San Jacinto, and totally defeated him. Santa Anna, to gain his liberty, signed a treaty recognizing the independence of the Republic of Texas. This treaty was never ratified by Mexico ; but the United States, and afterwards England, France, and Belgium, recognizing the new republic, its independence was practically secured. From this time the annexation of Texas to the United States became a great political issue, both by the Southern politicians, who were anxious to add more slave territory to the United States, and by Texas herself, whose finances had fallen into fearful disorder through careless and extravagant expenditures. This was not made possible until the election of James Polk to the Presidency, when the campaign cry of the South was, " Texas or Disunion." The first resolutions were introduced into Congress in the House, Jan. 25, 1845; by joint resolution, in the House, Dec. 16; and in the Senate, Dec. 22. Texas was admitted as a State without the formality of a treaty. It added 376,133 square miles to the territory of the United States.

The Mexican–American War (or Mexican War) was an armed conflict between the United States and Mexico from 1846 to 1848 in the wake of the 1845 U.S. annexation of Texas, which Mexico considered part of its territory despite the 1836 Texas Revolution.

American forces invaded and conquered New Mexico, California, and parts of what is currently northern Mexico; meanwhile, the American Navy conducted a blockade, and took several garrisons on the Pacific coast of Mexico—largely what is now California, but also farther south. Another American army captured Mexico City, which forced Mexico to agree to the sale of its northern territories to the U.S.

American territorial expansion to the Pacific coast was the goal of President James K. Polk, the leader of the Democratic Party. However, the war was highly controversial in the U.S., with the Whig Party and anti-slavery elements strongly opposed. Heavy American casualties and high monetary cost were also criticized. The major consequence of the war was the forced Mexican Cession of the territories of Alta California and New Mexico to the U.S. in exchange for $18 million. In addition, the United States forgave debt owed by the Mexican government to U.S. citizens. Mexico accepted the Rio Grande as its national border, and the loss of Texas. Meanwhile gold was discovered in California, which immediately became an international magnet for the California Gold Rush. The political aftermath of the war raised the slavery issue in the U.S., leading to intense debates that pointed to civil war; the Compromise of 1850 provided a brief respite.

In the U.S., the conflict is sometimes referred to as the Mexican War or the U.S.–Mexican War. In Mexico, terms for it include (primera) intervención estadounidense en México ((first) American intervention in Mexico), invasión estadounidense de México (American invasion of Mexico), and guerra del 47 (War of '47).

The California Gold Rush (1848–1855) began slowly on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill, in Coloma, California. The first to hear confirmed information of the gold rush were the people in Oregon, Sandwich Islands (Hawaii), Mexico, Peru and Chile and they were the first to start flocking to the state in late 1848. By 1850 the U.S. California Census showed 92,600 people in California to which about 30,000 more people should be added because the Censuses of San Francisco (the largest city in California at about 20,000 then), Contra Costa county and Santa Clara County were lost and not included in the total. The population of California was over 110,000 in late 1850 not including the Californios or the California Indians (who were not counted). The women who came to California in the early years were a distinct minority of less than 10% of the population. The news of the discovery brought some 200,000 people to California by 1852 from the rest of the United States and abroad. Of the 200,000, approximately half arrived by sea and half came overland on the California Trail and the Gila River trail.

The gold-seekers, called "Forty-niners" (as a reference to 1849, which is the year President James Polk declared a gold rush), often faced substantial hardships on the trip. While most of the newly arrived were Americans, the Gold Rush attracted tens of thousands from Latin America, Europe, Australia, and eventually China. At first, the prospectors retrieved the gold from streams and riverbeds using simple techniques, such as panning. More sophisticated methods of gold recovery developed which were later adopted around the world. At its peak, technological advances reached a point where significant financing was required, increasing the proportion of gold companies to individual miners. Gold worth tens of billions of today's dollars was recovered, which led to great wealth for a few. However, many returned home with little more than they had started with.

The effects of the Gold Rush were substantial. An estimated 100,000 California Indians died between 1848 and 1868 as a result of American immigration. San Francisco grew from a small settlement of about 200 residents in 1846 to a boomtown of about 36,000 by 1852. Roads, churches, schools and other towns were built throughout California. In 1849 a state constitution was written, a governor and legislature chosen and California became a state in 1850 as part of the Compromise of 1850.

New methods of transportation developed as steamships came into regular service as the first steamship--the SS California (1848) showed up in February 28, 1849. Soon steamships were carrying miners the 125 miles (201 km) up the Sacramento River to Sacramento, California. By 1869 railroads were built across the country from California to the eastern United States. Agriculture and ranching expanded throughout the state to meet the needs of the settlers. At the beginning of the Gold Rush, there was no law regarding property rights in the goldfields and a system of "staking claims" was developed. The Gold Rush also had negative effects: Native Americans were attacked and pushed off traditional lands and gold mining caused environmental harm.

The Oregon Trail is a 2,000-mile (3,200 km) historic east-west wagon route that connected the Missouri River to valleys in Oregon and locations in between. It flourished from the 1840s until the coming of the railroad at the end of the 1860s. The trip on foot took four to six months. It was the oldest of the northern commercial and emigrant trails and was originally discovered and used by fur trappers and traders in the fur trade from about 1811 to 1840. In its earliest days much of the future Oregon Trail was not passable to wagons but was passable everywhere only to men walking or riding horses and leading mule trains. By 1836, when the first Oregon wagon trains were organized at Independence, Missouri, the trail had been improved so much that it was possible to take wagons to Fort Hall, Idaho. By 1843 a rough wagon trail had been cleared to The Dalles, Oregon, and by 1846 all the way around Mount Hood to the Willamette Valley in the state of Oregon. What became called the Oregon Trail was complete even as improved roads, "cutouts", ferries and bridges made the trip faster and safer almost every year.

After 1840 steam-powered riverboats and steamboats traversing up and down the Ohio, Mississippi and Missouri rivers sped settlement and development in the flat region from the Appalachian mountains and the Rocky Mountains American. The boats serviced the jumping off points for wagon trains that crossed the mountains headed to rich farmlands in Oregon and California. With disputes with Spain and Britain settled by 1848, the new lands proved highly attractive. Getting there by sea meant either a very long trip around South America or through Panama—both were expensive and dangerous and took longer than walking.

The eastern part of the Oregon Trail spanned part of the future state of Kansas and nearly all of what are now the states of Nebraska and Wyoming. The western half of the trail spanned most of the future states of Idaho and Oregon. From various "jumping off points" in Missouri, Iowa or Nebraska, the routes converged along the lower Platte River Valley, near Fort Kearny, Nebraska Territory. Small steamboats carrying fur traders navigated the Missouri River up to the Yellowstone River in Montana as early as 1832. Larger steamboats traveling much above St. Joseph were blocked until dredging opened a bigger channel in 1852.

Oregon Trail travelers could purchase repairs, new supplies, fresh teams and help from fort-trading posts such as Fort Kearny and Fort Laramie. Jim Bridger's Fort Bridger and Hudson's Bay Company owned: Fort Hall and Fort Boise in Idaho; Fort Nez Perces (Fort Walla Walla) in Oregon and Fort Vancouver in Washington. Other supplies, fresh teams and repairs could often be obtained from temporary trading posts and ferries set up by entrepreneurs along the trail during the traveling season. From the early to mid 1830s, but especially after the organization of the first large wagon trains in Independence, Missouri in 1841 and through the epoch years 1846–1869 the Oregon Trail and its many off shoots was used by about 400,000 settlers, ranchers, farmers, miners, and businessmen and their families. The eastern half of the trail was also used by travelers on the California Trail (from 1843), Bozeman Trail (from 1863), and Mormon Trail (from 1847) which used many of the same eastern trails before turning off to their separate destinations.

Once the first transcontinental railroad by the Union Pacific and the Central Pacific was completed in 1869, the use of this trail by long distance travelers fell off because the train took seven days and at $69 was much cheaper. Travelers going to Oregon could take the train to California and catch a coastal steamer to Oregon. By 1883 the Northern Pacific Railroad had reached Portland, Oregon, and thereafter there were less and less wagon trains each year along the western trail. The legacy persisted as highways such as Interstate 80 followed the same course westward and passed through towns originally established to service the Oregon Trail.

To complete the journey in one traveling season most travelers left in April to May—as soon as there was enough grass for forage for the animals and the trails dried out. To meet the constant need for water, grass, and fuel for campfires the trail followed various rivers and streams across the continent. The network of trails required little initial preparation to be made passable for wagons. People using the trail traveled in wagons, pack trains, on horseback, on foot, and sometimes by raft or boat to establish new farms, lives, and businesses in the Oregon Country.