* 500,000 years ago: Repeated lava flows, ash, pumice ejections cause the volcano to grow.
* 75,000 years ago: The mountain probably reaches its present size.
* 6,600 to 5,700 years ago: Violent explosions cause mudßows that diminish the mountain's bulk.
* 5,800 years ago: Osceola Mudflow sweeps down both forks of the White River to beyond present-day Enumclaw.
* 3,000 to 2,500 years ago: The Columbia Crest forms during the mountain's last major eruptive period.
* May 7, 1792: British Capt. George Vancouver spots a "round snowy mountain" during an exploratory visit to Puget Sound. He names the peak Mount Rainier for his friend, Rear Adm. Peter Rainier.
* 1798: Vancouver publishes the name Rainier in his journal in London, kicking off the controversy over the mountain's name that lasts more than a century.
* Winter 1805-06: On their return trip to St. Louis, Meriwether Lewis and William Clark, who had spent a rigorous winter at the mouth of the Columbia River, spot Mount Rainier from about the present-day location of Portland.
* 1833: Dr. William Tolmie, a Hudson's Bay Co. physician at Fort Nisqually, ventures deep into what is now Mount Rainier National Park on a botanical survey. He becomes the first white man to enter what is now the park and the first to see glaciers in the United States.
* 1841: Lt. Charles Wilkes, in charge of the U.S. Exploring Expedition, triangulates Mount Rainier and comes up with a height of 12,330 feet - more than 2,000 feet too low. His failure to correct for the curvature of the Earth, atmospheric refraction and the height of his instrument above sea level probably accounted for the error.
* 1853: The Longmire family arrives in Yelm from Fountain County, Ind. Their group is the first to cross the Cascades north of the Columbia River.
* 1856: A U.S. Coast & Geodetic Survey calculates Rainier's height at 14,444 feet, but the surveyors aren't sure of the figure and don't publish the information until 1888.
* July 1857: A climbing party led by Army Lt. August Valentine Kautz makes it above 13,000 feet, but turns back because of snow blindness and exhaustion.
* 1862: Theodore Winthrop's travel book "The Canoe and the Saddle" makes the first known published reference to "Tacoma" as the Indian word for Mount Rainier.
* Aug. 17, 1870: First documented summit climb. Hazard Stevens (who called the mountain "Takhoma") and Philemon B. Van Trump were led part way up by Indian guide Sluiskin. They spent the night on the summit, surviving the cold by warming themselves at a steam vent. Sluiskin, who believed the climb impossible, thought they were ghosts when they returned the next day.
* Oct. 1870: Second successful ascent: Samuel F. Emmons and A.D. Wilson
* 1881-82: Bailey Willis, a Northern Pacific Railroad geologist, cuts a horse trail from Wilkeson up the Carbon River to the Carbon Galcier. Willis writes of enormous trees, awesome silence and oppressive solitude. He calls the mountain "an awful power clad in beauty."
* 1883: Northern Pacific Railroad first suggests Mount Rainier and its glaciers be established as a national park and sends a party of influential writers to the area.
James Longmire, searching for lost horses, discovers natural mineral springs at what is now Longmire.
Tacomans make their first serious attempt to change the name of the mountain to Mount Tacoma.
* 1884: Longmires construct first trail to mineral springs.
* 1885: James Longmire's wife, Virinda - or Martha, the wife of his son Elcaine - visits Paradise Valley for the first time and names it Paradise because of the beauty of the wildflowers.
The Rev. Warner Fobes, Richard O. Wells and George James of Snohomish attempt the first ascent via the north side. They reach the summit on the third try.
* 1888: Naturalist John Muir visits Mount Rainier and climbs to the summit with Maj. Edward S. Ingraham. "Did not mean to climb it," Muir wrote in a letter to his wife, "but got excited and soon was on top."
The Tacoma City Council asks the Territorial Legislature to petition Congress to set aside Mount Rainier as a national park.
* 1889: Longmire family completes two bathhouses and some guest cabins at the mineral springs and begins advertising "Longmire's Medical Springs" in Tacoma newspapers.
* Nov. 11, 1889: Washington becomes the 42nd state.
* Aug. 10, 1890: Fay Fuller, a teacher from Yelm, is the first woman to reach the summit. Age 20 and single, her climb alone with four men scandalized Tacoma society. So did her climbing costume - a long skirt with ankle-length bloomers, boys shoes and a straw hat.
* 1890: U.S. Board of Geographic Names decides "Rainier" must remain on all government maps and publications.
* 1890-91: With help of Indian laborers, the Longmires clear a crude wagon road from Ashford to the springs. They build the mountain's first hotel, Mineral Springs Resort.
* 1891: First dog climbs the mountain - a deerhound belonging to Dr. Warren Riley, who accompanied Van Trump.
* 1893: Land that is now Mount Rainier National Park is set aside as a federal forest reserve - the precursor to what are now called national forests. The "Pacific Forest Reserve" was roughly a square, 35 miles on a side, with Mount Rainier on its western edge.
A map at the Chicago World's Fair shows the name of the peak as "Mount Tacoma or Rainier." The map causes such a controversy that it is banished to a back room.
* Dec. 1893: Washington Sen. Watson C. Squire introduces a bill in Congress to establish "Washington National Park." It was the first of six bills introduced in consecutive sessions of Congress before the park was finally established in 1899.
* 1894: Last known eruption, a minor emission of smoke and ash confirmed by a climbing party led by Maj. E. S. Ingraham.
Seattle-brewed Rainier beer makes its debut.
* 1895: The Tacoma Ledger reports vandals setting fire to large trees at Paradise to watch them burn, raising public outrage and strengthening the argument that the mountain needs national park status to preserve it.
* 1896: Road to Longmire is improved enough to accommodate stagecoaches.
Geologist Israel C. Russell thoroughly explores and maps the mountain.
* Feb. 22, 1897: The Pacific Forest Reserve is enlarged and its name changed to "Mount Rainier Forest Reserve."
* 1897: University of Oregon professor Edgar McClure carries a barometer to the summit in an effort to measure its height, then dies in a fall on his way down - the first climbing fatality recorded on the mountain.
* March 2, 1899: President William McKinley signs a bill authorizing the creation of Mount Rainier National Park, making it the nation's fifth national park.
* 1901: The Washington Legislature cedes exclusive jurisdiction over the national park to the United States. But Congress doesn't accept until 1916, creating problems for the park's share of federal appropriations.
* 1903: U.S. Rep. Francis W. Cushman persuades Congress to authorize $10,000 for a better highway from Ashford to Paradise. The task goes to the Army Corps of Engineers.
* 1904: Tacoma & Eastern Railroad reaches Ashford, seven miles from the park boundary. Visitors are shuttled to the park by stagecoach.
* 1905: Robert Longmire opens a saloon in the park. The park's acting superintendent, Grenville F. Allen, immediately closes it down, calling it a public nuisance.
During a joint outing of the Sierra Club, the Portland Mazamas and two other clubs, 112 climbers reach the summit.
* 1906: The Park Service turns in its first official count of visitors: 1,786.
National Park Inn opens at Longmire.
Construction starts on road from Longmire to Paradise.
Seattle-area members of the Portland-based Mazamas split off to form The Mountaineers.
* 1907: First automobile permitted into the park, making Mount Rainier the first national park to allow cars.
* 1908: Congress bans new mining in the national park. Existing claims are unaffected.
* 1909: The Alaska-Yukon-Pacific Exposition, located at what is now the Seattle campus of the University of Washington, opens on Lake Washington, designed around a view of Mount Rainier.
* 1910: Francois E. Matthes begins a topographical survey of park, which leads to the Þrst accurate map.
The Army Corps of Engineers completes the new road to Paradise Valley. Cost is $240,000.
* 1911: President William Howard Taft visits Rainier. The president's touring car becomes mired in mud short of Paradise and has to be towed by mule team.
First sewer system installed at Longmire.
The welcome arch of massive peeled cedar logs is built at the Nisqually entrance.
* 1912: Civic boosters organize the Seattle-Tacoma Rainier National Park Committee (later the Rainier National Park Advisory Board). The unofficial group dedicates itself to the "development and exploitation of Mount Rainier National Park." Photographer Asahel Curtis is its first chairman.
The Kum-an-go Transportation Co. gets a permit to operate a 17-passenger auto shuttle from Nisqually to Longmire to the Nisqually Bridge.
Olive Rand becomes the first person known to have skied on Mount Rainier. She brought makeshift skis along on a winter outing sponsored by the Tacoma Mountaineers.
* 1913: C.H. Birdseye leads U.S. Geological Survey party that determines Columbia Crest's position and altitude: 14,408 feet.
* 1914: Women are allowed to drive on park roads.
* 1915: Road to Paradise opens to the public.
The system of trails now known as the Wonderland Trail is completed, making it possible to walk completely around the mountain.
* 1916: Seattle and Tacoma businessmen form The Rainier Na tional Park Co. to provide tourist facilities inside the park.
The National Park Service is created and given full jurisdiction over the park.
* 1917: Paradise Inn opens. It's built with silver forest logs. Cost is about $100,000.
* 1918: First campsites constructed.
* 1924: Senate passes a resolution to change name to Mount Tacoma; House kicks it back to the U.S. Board of Geographic Names, which says no, again.
* 1929: Six climbers slide into a crevasse on their way down the mountain. Guide Forrest Greathouse and one client, Edwin Witzel, die. The notch through which their bodies are transported down the mountain becomes "Cadaver Gap." The Park Service begins requiring crampons or caulked boots on climbs.
* 1931: New road to Sunrise and Sunrise Lodge opens, along with 215 cabins. The Rainier National Park Co. markets Sunrise as a dude ranch and opens a nine-hole golf course at Paradise. Ohanapecosh area is added to the park.
* 1933: Park visits fall to 7-year low - 170,194 - in the depth of the Depression.
Civilian Conservation Corps work camps are established in the park. By the mid-1930s, nearly 1,000 young men were at work refurbishing trails, picnic areas and campgrounds; building bridges and shelters and maintaining phone and power lines.
* 1934: The Post Office issues a 3-cent Mount Rainier stamp as part of its National Parks commemorative series. The stamp shows the mountain from Mirror Lake. It's the first of three stamps with a likeness of the mountain. The others were issued in 1953 (Washington Territory centennial) and 1989 (Washington statehood centennial).
* 1935: U.S. Olympic downhill ski team tryouts are held in the park before 7,500 spectators. CBS Radio covers the events live.
* Winter 1936-37: Part of the narrow ledge along the face of Gibraltar Rock falls away. That had been the route of choice for most climbers since the first summit climb in 1870.
* 1938: Paradise is the busiest ski resort in the Northwest, with daily classes and night skiing under floodlights.
* 1939: Sigurd Hall makes the first ski ascent of the mountain. The first complete ski descent wasn't made until 1948.
* 1940: Hall is killed in an accident during the Silver Skis race on the mountain.
* 1942: Ski troops from the 10th Mountain Division stationed at Fort Lewis train on Mount Rainier.
* June 22, 1945: President Harry S Truman pays a quick surprise visit to Mount Rainier. He throws snowballs at Paradise, plays the piano in the Paradise Inn, shakes hands with the staff and spends a half-hour talking and pitching pennies with Park Superintendent John Preston.
* 1946: Number of visitors to Mount Rainier breaks all previous records at 468,225.
* Dec. 10, 1946: A Marine C-46 crashes into Success Cleaver, killing all 32 men aboard - the worst of about a dozen fatal civilian and military plane crashes on the mountain over the years.
* June 24, 1947: Pilot Kenneth Arnold reports seeing nine mysterious flying objects shooting past the mountain, marking the beginning of international interest in UFOs.
* 1952: Twins Jim and Lou Whittaker take over the climbing concession at Mount Rainier.
The Department of Interior buys out the Rainier National Park Co.
* 1955: In a particularly bad weather year, the Nisqually River bridge is destroyed by a flood in October and in December, a large mudslide covers the Mountain Highway four miles west of Eatonville, cutting off access to most of the west side of the park. The road remains closed to this day.
* 1956: A new United States Geological Survey measurement places Mount Rainier's height at 14,410 feet.
* 1960: Congress OKs building a new park headquarters, Tahoma Woods, outside of the park near the town of Ashford. Buildings were completed and occupied in 1976.
* 1962: Seattle World's Fair crowds boost park attendance to a new record high of 1,905,302.
The American Mount Everest Expedition team trains on Mount Rainier. Jim Whittaker becomes the first American to conquer Everest the following year.
* 1965: The Paradise Lodge is burned to make room for new parking, and construction begins on a new saucer-shaped Paradise Visitors' Center. The new center costs $2 million, making it the most expensive structure in the entire national park system.
* 1967: A surprise mudflow off the Tahoma Glacier buries the Tahoma Creek Campground.
* 1968: Lou Whittaker and a partner form Rainier Mountaineering Inc., now the oldest continually operating guide service and climbing school in the U.S.
* Winter 1971-72: 72.93 feet of snow falls on Paradise, a U.S. record.
* March 4, 1979: Climber and teacher Willie Unsoeld and an Evergreen State College student die in an avalanche on Cadaver Gap.
* March, 1980: The park is closed briefly after the eruption of Mount St. Helens.
* June 21, 1981: Eleven climbers die in an avalanche on Ingraham Glacier, the worst climbing accident in U.S. history.
* 1988: Federal legislation designates most of Mount Rainier National Park as "wilderness" under the Washington Park Wilderness Act.
* 1989: Satellite measurement done for the state centennial adds 13 inches to Mount Rainier's height: 14,411.1 feet.
* 1990: A November storm dumps 14 inches of rain in five days. The Westside Road is washed out.
* 1994: Gasoline sales within the park end.
* 1996: Nasty winter weather washes out the Carbon River Road and severly damages the Cayuse Pass Highway (Washington 123).
Entrance fee doubles to $10.
* 1998: An avalanche on June 11 kills one and injures 11.
The Carbon River road reopens in November, but continues to be plagued by problems due to rain.
* March 2, 1999: Mount Rainier National Park turns 100.
* 2004: Three accidents on Liberty Ridge claim four climbers.
* 2006: Park entry fee jumps to $15.
* Nov. 6-7, 2006: Flooding does more than $30 million in damage to the park and forces the longest closure since World War II.
* 2007: International Mountain Guides and Alpine Ascents join RMI as the only guide services allowed to take climbers up Rainier.