1803 - President Thomas Jefferson purchased the Louisiana Territory from the French
1804 to 06 - Meriwether Lewis and William Clark left the East for an expedition to the Oregon Territories to find a water route to connect the seas and learn about new peoples, plants, and animals.
1812-13 - John Jacob Astor and "the Astorians" headed to the Pacific Coast via the Oceans and over land to get in on a bit of the fur trade that the Hudson's Bay company had a monopoly on. Robert Stuart led part of the group back to Missouri over land. He heard about the "south pass" but didn't use it.
1818 - Treaty of 1818 signed between US and Great Britain, fixing northern border at the 49th parallel between Minnesota and the Rocky Mountains, and providing for Joint Occupation of the Oregon Territory.
1819 - Adam-Onis Treaty signed between US & Spain setting the 42nd parallel as Southern boundary between Oregon & Mexico.
1820's - Western fur trade on fur-bearing animals living on land in the territory began ramping up and hit its climax during the 1830's, then tapered off by the 1840's.
1824 - Russia agreed to the 54'40' parallel as Alaska's southern border, which set the Oregon territory's Northern border. Fur trapper's rendezvous' began under William Henry Ashley. Future wagon train pilots such as Tom Fitzpatrick, Jim Clyman, Jed Smith, Jim Bridger, Bill Sublette, and Joseph Walker began with this. Some of them traversed and clearly identified South Pass. Independence Rock was named.
1825 - Fort Vancouver established as a Fur Trade center on the Columbia by the Hudson's Bay Company. Dr. John McLoughlin was chief factor.
1827 - Independence, Missouri became the "jumping off" point for the Santa Fe Trail. Fort Leavenworth was established as a military post on the Santa Fe Trail. During the gold rush it became another "jumping off" point in westward journeys.
1830 - The Smith-Jackson-Sublette caravan heading to the rendezvous at Lander, Wy brought the first ten wagons of supplies toward the west.
1831 - Christian groups began the process of sending missionaries west.
1832 - Captain Benjamin Bonneville headed a wagon train west through South Pass into Idaho. Hall Jackson Kelley formed the American Society for Encouraging the Settlement of the Oregon Territories.
1834 - Fort William was established by a group of trappers near the mouth of the Laramie River. Nathaniel J. Wyeth built Fort Hall on the Snake River for the fur trade business, but ended up selling it to the Hudson's Bay Company. For emigrants on the Oregon Trail it represented the completion of two-thirds of the journey. Jason Lee headed west to setup Christian missions. Thomas McKay built Fort Boise for the Hudson's Bay Company.
1836 - Dr. Marcus Whitman set up a mission at Waiilatpu, near Walla Walla.
1838 - Daniel Lee established the Wascopan Methodist Indian Mission in the Dalles, which proved a great help to the emigrants as they arrived there for the last leg of their journey.
1838-39 - The Shawnee Methodist Mission was established in Kansas and became an early stopping point for emigrants.
1840 - Father Pierre-Jean DeSmet set up mission in the west.
1841 - First emigrant wagon company left for the Oregon Territories, led by John Bidwell and John Bartleson and guided by Thomas Fitzpatrick and Joseph Meek. The party split into Oregon and California groups near Fort Hall.
Fort John replaced Fort William on the Laramie River. Arriving at this fort (called Fort Laramie by emigrants) signaled the end of the first third of their journey.
1842 - Lt. John C. Fremont, guided by Kit Carson led a trip of exploration west and created maps and geographical information for future travelers. Oregon City was formally platted by Dr. John McLoughlin. Oregon City began to serve as the "end of the Oregon Trail." Dr. Elijah White, guided at times by James Coates, Stephen Meek, and Tom Fitzpatrick led 30 wagons and 112 people west - including Lansford Hastings. Horace Greeley began writing about Oregon and the West.
1842-43 - Jim Bridger and Louis Vasquesz constructed Fort Bridger.
1843 - Joseph Robidoux established the city of St. Joseph, later known as St. Joe, which became a popular "jumping off" point for wagon trains. The first of the large migrations with 875 people and up to 200 wagons led by Marcus Whitman and John Gannt among others left for the west. Peter Burnett and Jesse Applegate joined this train.
The Oregon provisional government was established on May 2nd, with Oregon City as the Capitol and George Abernethy as Governor.
1844 - Three major wagon trains left for Oregon. The trail route began bypassing Whitman mission to save miles and time. The Greenwood or Sublette cutoff was opened, saving 75 miles and 4 days of travel. It included a 50 mile lack of water, but many chose it anyway. James K. Polk was elected president and began talks with Great Britain over conflicts of ownership in Oregon.
1845-46 - Sam Barlow and Joel Palmer blazed a new route through the cascades around the south side of Mt. Hood. Barlow and Philip Foster chartered the road as a toll road and began charging emigrants to use it. It became well-used despite the treacherous Laurel Hill "chute" as most people found it safer than the river. During its first year of use, 153 wagons and 700 people used it. The early charges were $5 per wagon and $0.10 per animal. The 'Barlow Road' was used until 1920.
1846 - US signed a treaty with Great Britain marking the 49th parallel as the northern border between the Rocky Mountains and the Pacific Ocean.
Congress approved an act to provide military protection on the trail, but the Mexican War delayed action.
The Applegate Trail opened bringing people into Oregon from the South. 21
1847 - The Mormon migration began to the areas the Great Salt Lake valley. Council Bluffs was set up as a "jumping off" point by Brigham Young, and used later by all. Measles killed many near the Whitman mission, causing retaliation by the Cayuse in the area and a massacre that killed many at the mission.
1848 - Oregon became an official US Territory. Fort Kearny was built on the Platte River to serve for protection and supplies to emigrants and military.
1849-50 - Cholera killed up to two thirds of some wagon companies in 49,50 & 52. The Gold Rush took many people south to California once they passed Fort Hall.
1849 - Robidoux established a small trading post near Scott's Bluff and Robidoux Pass(which was used heavily by emigrants until 1853.) The military presence became active along the Oregon Trail with several new forts being built or taken over by the military. Fort Laramie was established as a military post. Benoni Hudspeth took a shortcut from Soda Springs to the Raft River and the California Trail which became known as the Hudspeth cutoff.
1850 - Fort Dalles was established in The Dalles to protect the emigrants. Judge Samuel Woodson and James Brown established regular mail service from Independence to Fort Bridger and Salt Lake.
1851 - Mitchell Pass began to be used by emigrants and replaced Robidoux Pass. At Horse Creek, west of Scott's Bluff one of the largest treaty councils was held with over 10,000 people from 12 plains nations.
1854 - Near Fort Laramie an emigrant‟s cow wandered off and was killed and eaten by a nearby village. The military was called in by the emigrant and created a conflict that ended with the deaths of most of the military and many of the native peoples involved. One soldier got away and reported the "massacre," beginning many years of conflict and war. Another incident happened which caused death and strife between the Native Americans and the military when an emigrant shot someone trying to steal a horse.
1855 - The military went out to avenge the prior year's massacres and executed those responsible for them.
A treaty council happened with people of eastern Oregon, Washington and Idaho which established reservations and claimed lands for the emigrants. Emigrants came in to take over before arrangements had been made for reservations and fighting happened.
1858 - The army rebuilt Fort Bridger which served them until 1890. Fort Caspar was established in Central Wyoming near a crossing of the North Platte River.
1859 - The Lander Road cutoff was built, saving emigrants 100 miles. This was a late construction which didn't play a major role in the migration history.
Oregon became a state.