Black Diamond is a city in King County, Washington, United States.

[4] In 2023, with a 40.6% growth rate,[5] Black Diamond was the fastest growing small city in King County.

[6] Black Diamond was originally inhabited by the Bəqəlšuł, which is Lushootseed for "from a high point from which you can see", part of Coast Salish people.

The area was home to a grill trap and smokehouse, and the tribe fished from Lake Sawyer.

[11] The original residents were largely composed of former workers, from the company's previous coal mining operation in Nortonville, California, which primarily sold coal to the thriving new metropolis of San Francisco.

[12] A combination of low quality coal from the Nortonville mines, water intrusion into the workings there, and the discovery and economical transport of higher-quality Washington coal to San Francisco spelled the demise of Nortonville in the early 1880s.

[13] The town was home to around 3,500 people by the early 1900s, many of them European immigrants; most of the working men were involved in producing coal.

Mining has continued until recently through the Pacific Coast Coal Company, formerly of San Francisco.

[citation needed] The main building of the Black Diamond Historical Museum is the former train station, which served the Seattle and Walla Walla Railroad 1884–1916 and the Pacific Coast Railway 1916–1951.

[citation needed] In the 1990's, the first Black Diamond city planner (Jason Paulsen), seized an opportunity to create a comprehensive development plan for the City of Black Diamond that when completed, would fundamentally change what and how the City of Black Diamond would evolve into — the first set of plans being the Growth Management Act (GMA) Comprehensive Plan, which included the concept of Master Planned Developments (MPDs).

[21][22] From 2010 through 2018 legal battles were fought delaying development of the first MPDs: The first two MPDs comprised 6,050 single and multi-family residences, 1.1 million square feet of commercial/office/retail space and were estimated to 15,000 new residents to the City of Black Diamond;[21] which would increase the population of the city by 3.6 times its size at the time (2010 population estimate of 4,151).

[31] In 2021, with a 21% growth rate,[5] Black Diamond was the fastest growing small city in King County.

[32] Using King County's 2020 Person's per household rate of 2.43,[33] 845 households being occupied in Ten Trails in March 2022,[32] the estimated population of Black Diamond in 2022 being 6,336,[5] concludes the estimated population living in Ten Trails in March 2022 being 2,053 (845[32] * 2.43[33]); which roughly equates to 79% ( 2,053 / 6,336[5]) of the population of Black Diamond living in the first MPD (Ten Trails) during March 2022.

While Donald Trump carried the city twice, he did so both times by small margins.

[43] The minor-league baseball star Edo Vanni was born at Black Diamond in 1918.