The area near the confluence of Icicle Creek and the Wenatchee River in modern-day Leavenworth is within the traditional territories of the indigenous Wenatchi and Yakama peoples.

[11] The Stevens Pass route, which connected Seattle to Wenatchee, was completed in January 1893 and was the final section of the transcontinental Great Northern Railway.

[18] In 1962, the Project LIFE (Leavenworth Improvement For Everyone) Committee was formed in partnership with the University of Washington to investigate strategies to revitalize the struggling logging town.

The idea to create a "Bavarian-Swiss" alpine theme town came from two Seattle businessmen, Ted Price and Bob Rodgers, who had bought a failing cafe at Coles Corner in 1960.

[19] Price and Rodgers had chosen the theme based on the latter's experience in Bavaria while deployed by the U.S. Army during World War II; the cafe was renamed The Squirrel Tree and expanded with a motel and gift shop.

[20] Price was chair of the Project LIFE tourism subcommittee, and in 1965 the pair led a trip to a Danish-themed town, Solvang, California, to build support for the idea.

[21][22] By 1970, Leavenworth was hosting several annual festivals and had formed a design review board to enforce and maintain the standards set by Project LIFE.

About 30 million years before present in the Oligocene epoch, the Chiwaukum graben underwent compressional deformation creating several folds in the region that are visible today.

The area to the west and southwest of Leavenworth was created in the middle Cretaceous period with the uplift of the Mount Stuart batholith, forming the granite rock seen today in Icicle Ridge and Tumwater Mountain.

During the Pleistocene and into the Holocene epochs, an alpine glacier originating from the southwest in the Mount Stuart range made its way to where the town is today.

Leavenworth sits on the terminal moraine of that glacier and has many glacial erratics that originated 20 miles up the Icicle Valley near Mount Stuart.

The temporary dam, in conjunction with one of the Lake Missoula floods, caused the water to flow back up the Wenatchee Valley, where it was stopped by the glacier at Leavenworth.

As the leading edge of the glacier interacted with the flood, ice rafts formed carrying granite erratics from the Stuart batholith, which ended up in the town of Dryden about 15 miles down the valley from Leavenworth.

Leavenworth has a continental Mediterranean climate (Köppen Dsb) with summers characterized by hot, sunny days and chilly nights, and cold, snowy winters.

Leavenworth was designed with an Alpine German theme from the 1960s onward, with most buildings modeled after Bavarian settlements and adopting stereotypical fonts and names.

[44] The city hosts an annual Christmas tree lighting celebration in December that draws thousands of visitors and causes congestion on local highways.

[48] An adventure park that comprises a climbing wall and alpine coaster with 2,700 feet (820 m) of track and opened in 2023 on a hill on the southwest side of the city.

[61] Unlike the rest of Chelan County, Leavenworth has voted for the Democratic Party's candidate by wide margins in presidential elections since 2012.

[73] A park-and-ride lot in downtown Leavenworth with 30 stalls is served by Link Transit,[74] along with the Wilkommen Park and Ride opened in June 2019.

[75] The city also has several private taxi companies and inter-city bus operators, including stops for Northwestern Trailways and Amtrak Thruway.

[78] The Leavenworth city government provides tap water to over 1,404 residential and commercial customers with an estimated annual use of 320 million US gallons (1.2 billion litres).

[79] Its primary source is Icicle Creek, which originates in the Cascades near Stevens Pass and also serves a federal fish hatchery and nearby orchards.

[80][81] The city's use of Icicle Creek was the subject of a decade-long dispute with the Washington State Department of Ecology and conservationists that was settled in 2023 with a revised water rights agreement.

[83] Leavenworth has one public hospital, Cascade Medical Center, with 12 beds designated for acute care and an on-site rural health clinic.

[85] A public hospital district was formed in 1965 to fund a new building, which opened in the following decade with 33 beds and was named the Cascade Medical Center.

[89] Cascade sold its bed licenses to the Wenatchee Valley Clinic in 2001 for $2.5 million to resolve its remaining debt and end the partnership.

[91] The new hospital opened in November 2010 with a new acute care unit;[86] it was followed by renovations in 2011 to the existing building to house lab space and a larger lobby.