[4] The British Crown sent out surveyors to mark the border between its two colonies of Canada and America in accordance with the Quebec Act of 1774.

This latter tract nearly corresponded with the old New York county of Gloucester, organized by that province March 16, 1770, with Newbury as the shire town.

[8] On September 3, 1783, as a result of the signing of the Treaty of Paris the Revolutionary War ended with Great Britain recognizing the independence of the United States.

[7] In 1810, Runaway Pond suddenly flooded the Barton River Valley with 1,988,000,000 US gallons (7.53×109 L; 1.655×109 imp gal)[14] of water in the greatest natural catastrophe in Orleans County post-Columbian history.

On December 27, 1813, the county was invaded by British militia from nearby Stanstead, Quebec, during the War of 1812 in order to destroy an undefended barracks at Derby and to forage for supplies.

[17] When Lamoille county was formed in October 1835, Orleans lost the towns of Eden, Hyde Park, Morristown, and Wolcott.

[22] In 1864, 267 men from the 11th Vermont Infantry were captured at the Battle of the Weldon Railroad in the Overland campaign.

Like the rest of the state, Orleans County sent up to one-quarter of its eligible men to the Civil War.

[26] As a result of this and loss of native farm labor to other states, Vermont, particularly the northern part, saw many immigrants then and through the turn of the twentieth century.

In 2008, the state notified residents of Albany, Craftsbury, Irasburg, Lowell, Newport Town, Troy, Westfield and six towns in the adjacent counties of Lamoille and Franklin, that a review of health records from 1995 to 2006 had revealed that residents within 10 miles (16 km) of the former asbestos mine on Belvidere Mountain had higher than normal rates of contracting asbestosis.

[30][31] A critic replied that the entire basis of the study were three unidentified people who died from asbestosis 1995-2005 out of a total population of 16,700.

[32] In April 2009 the Vermont Department of health released a revised study which found that all of deaths related to the asbestos mine were caused by occupational exposure.

The county is unique in eastern Vermont for mostly draining north as a part of the St. Lawrence River basin.

The area is conducive to songbirds because of its northern location, boreal forests, mountain peaks, bodies of water and marshes.

One inventory in June 2012 found the following species: ovenbird, eastern whip-poor-will, Wilson's snipe, alder flycatcher, warbling vireo, red-eyed vireo, winter wren, wood thrush, American robin, veery, gray catbird, common yellowthroat, chestnut-sided warbler, northern waterthrush, black-throated green warbler, northern parula, American redstart, white-throated sparrow, indigo bunting, red-winged blackbird, American goldfinch, osprey, ring-necked duck, hooded merganser, pied-billed grebe, double-crested cormorant, great blue heron, bald eagle, Virginia rail, American herring gull, ring-billed gull, chimney swift, belted kingfisher, marsh wren, house wren, eastern bluebird, pine warbler, black-and-white warbler, Savannah sparrow, northern cardinal, eastern meadowlark, bobolink, bank swallow, cliff swallow, barn swallow, white-breasted nuthatch, ruffed grouse, ruby-throated hummingbird, blue-headed vireo, red-breasted nuthatch, Lincoln's sparrow, rose-breasted grosbeak, pine siskin, purple finch, Canada warbler, magnolia warbler, Nashville warbler, golden-crowned kinglet, mourning warbler, dark-eyed junco, and northern rough-winged swallow.

Also known to be in the area were: wild turkey, American bittern, broad-winged hawk, peregrine falcon, pileated woodpecker, hairy woodpecker, scarlet tanager, American woodcock, Bicknell's thrush, blackpoll warbler, yellow-bellied flycatcher, broad-winged hawk, and Swainson's thrush.

], blue jay, Barrow's goldeneye, Lapland longspur, white-winged scoter, olive-sided flycatcher, red crossbill, Bonaparte's gull, and rough-legged hawk.

[46] On February 5, 1995, Jay Peak received 42.0 inches (107 cm) of snow, the greatest daily snowfall recorded for any location in Vermont.

[58] The Assistant, or "Side," Judges, Superior Court, approve the budget for county expenses.

She was appointed originally by governor Phil Scott to fill the remaining vacancy from Kirk Martin, who retired.

[66] The sheriff's department made national news in 2012, when a driver of a large tractor deliberately drove over and wrecked at least six cruisers, out of a fleet of 11.

In 1828, Orleans County was won by National Republican Party candidate John Quincy Adams.

From William Henry Harrison in 1836 to Winfield Scott in 1852, the county voted for the Whig Party candidates.

Following Johnson's victory in 1964, the county returned to voting for Republican candidates for another 20 years, starting with Richard Nixon in 1968 and ending with George H. W. Bush in 1988.

[85] Wheeler Mountain Academy, grades 7–12, aids students who have emotional, behavioral or learning challenges.

In 2008, there was no correlation between the performance of students on the standardized New England Common Assessment Program tests and poverty (free lunch).

Mount Owls Head in Canada may provide "roaming" service of Canadian carriers in the North part of the county.

The last exit, 29, which is located less than ¼ mile from the Canada–US border, leads to the village of Derby Line and the town of Holland.

The RCT (Rural Community Transportation), a non-profit organization, runs out of Saint Johnsbury and services Caledonia, Essex, Lamoille and Orleans Counties.

[107] Washington County Railroad (The Vermont Railway System) - WACR has just recently been awarded a 30-year contract to operate the track running from White River Junction North through St. Johnsbury and Newport.