[5] The name "Death's Door" came from Native American tales, heard by early French explorers and published in greatly embellished form by Hjalmar Holand, which described a failed raid by the Ho-Chunk (Winnebago) tribe to capture Washington Island from the rival Pottawatomi tribe in the early 1600s.

[6] The earliest known written reference to the legend is from Emmanuel Crespel [fr], who termed the peninsula "Cap a la Mort" in 1728.

[9] In 1853, Moravians founded Ephraim after Nils Otto Tank resisted attempts at land ownership reform at the old religious colony near Green Bay.

[12] In the 19th century, a fairly large-scale immigration of Belgian Walloons populated a small region in the southern portion of the county,[13] including the area designated as the Namur Historic District.

They built small roadside votive chapels, some still in use today,[14] and brought other traditions over from Europe such as the Kermiss harvest festival.

[15] Shortly after the 1831 Treaty of Washington,[16] the federal government surveyed what is now Door County to determine the value of the timber and to divide up parcels for eventual sale.

[19] At the time the Homestead Act of 1862 was passed, most of the county's nearly 2,000 farmers were squatters earning most of their revenue from lumber and wood products.

The area of this disaster is now Tornado Memorial County Park, named for a fire whirl which occurred there.

[26] Even after the Ahnapee and Western extended service to Sturgeon Bay in 1894, many tourists continued taking the railroad to Menominee, Michigan[a] to embark on steamships bound for communities in Door County.

This route over Green Bay bypassed poor road conditions in the northern part of the county, which persisted until the early 1920s.

Only after crushed stone highways were built did motor and horse-drawn coaches become popular for transportation between Sturgeon Bay and the northern part of the peninsula.

[42][43] The county has a humid continental climate (classified as Dfb in Köppen) with warm summers and cold snowy winters.

Data from the Peninsular Agricultural Research Station north of the city of Sturgeon Bay gives average monthly temperatures ranging from 68.7 °F (20.4 °C) in the summer down to 18.0 °F (−7.8 °C) in the winter.

The moderating effects of nearby bodies of water reduce the likelihood of damaging late spring freezes.

[49][c] Additionally, Plum Island and Green Bay National Wildlife Refuge are seasonally open for public recreation.

[54][55] Tamias striatus doorsiensis, a subspecies of eastern chipmunk, is only found in Door, Kewaunee, Northeastern Brown, and possibly Manitowoc counties.

[56] In 1999, the Wisconsin Natural Heritage Inventory listed 24 aquatic and 21 terrestrial animals in Door County as "rare.

[58] Kangaroo Lake State Natural Area has the largest breeding population of the endangered Hine's Emerald Dragonfly in the world.

Including lighthouses, the county has 72 properties and districts listed on the National Register of Historic Places.

[70] Scandinavian heritage-related attractions include The Clearing Folk School, two stave churches,[71] structures in Rock Island State Park furnished with rune-inscribed furniture,[72] and Al Johnson's Swedish Restaurant, which features goats on its grassy roof.

In Ephraim, the Village Hall, the Moravian and Lutheran churches, and the Peter Peterson House are listed in the National Register of Historic Places, as is the L. A. Larson & Co. Store building in Sturgeon Bay.

[90] A daily private shuttle service operates between Green Bay–Austin Straubel International Airport and Sturgeon Bay.

[136] In 2014, the voluntary intoxication defense in Wisconsin was repealed due to outcry following its use during a trial in Door County.

President Clinton was the last candidate, up until 2024, to win nationally without carrying Door County in the 1992 presidential election.