MUKILTEO

Early 20th century

The Seattle and Montana Railroad (later part of the Great Northern Railway) was completed in 1891, connecting Mukilteo with Everett, Edmonds, and Seattle. Mukilteo was platted in anticipation of the railroad and was on the shortlist of towns considered for the terminus of the Northern Pacific Railway, but lost out to Tacoma in 1873. Following the 1890s economic depression, the town experienced a major employment and population boom, with a larger lumber mill and gunpowder factory both built along the shore. The iconic Mukilteo Lighthouse was built in 1906 by the federal Lighthouse Service to serve the increased maritime traffic in the area.

Japanese immigrants arrived to work in Mukilteo's mills after the turn of the century, establishing a Japantown in modern-day Japanese Gulch. Passenger ferry service between Mukilteo and Whidbey Island began in 1911 and was followed by the introduction of automobile ferry service in 1919. The town also gained a highway connection in 1914 with the completion of a road to Everett, later named Mukilteo Boulevard by the 1920s. Until the closure of the lumber mill in 1930, Mukilteo was a company town that relied on the Crown Lumber Company to assist in civic endeavors, including its parks, fire department, and water district; at its peak, it employed 250 men.

During the Prohibition Era, Mukilteo became a major transiting point for rum-running and was a stopover for smugglers transporting alcohol from British Columbia to Seattle. The town's gunpowder plant was destroyed on September 17, 1930, in an after-hours explosion that leveled or damaged dozens of homes, causing $500,000 in damage. It was felt as far as downtown Everett and injured eight people, but none were killed. On August 30, 1938, the vacant lumber mill was destroyed in a fire during dismantling work. The fire came weeks after a mail ferry rammed into the town's wharf, which was destroyed in the collision.

After the United States entered World War II, the site of the former lumber mill was acquired by the federal government and rebuilt as a 1,500-foot-long (460 m) ammunition loading dock for warships. The recently built Snohomish County Airport (later renamed Paine Field) southeast of the city was converted into a military base while retaining some civilian uses, including passenger service provided by Alaska Airlines. During the early 1950s, the loading dock was expanded with ten large storage tanks that were used to store jet fuel for military planes until 1989.

Incorporation and late 20th century

On April 29, 1947, Mukilteo residents voted 223 to 137 in favor of incorporating as a fourth-class city and elected school administrator Alfred Tunem as its first mayor. The incorporation was certified by the state government on May 8; at the time, Mukilteo had an estimated population of 775 people and encompassed 794 acres (321 ha). The new municipal government took over services that were previously handled by the self-organized Mukilteo Improvement Club, which was established in the 1930s. The area experienced additional population and commercial growth after the opening of Boeing's Paine Field factory for passenger jetliners in 1967, which was connected to Mukilteo by a short railroad along the floor of Japanese Gulch. The Boeing Freeway was opened in 1969, linking southern Mukilteo and the Boeing plant to a junction with Interstate 5 near the newly built Everett Mall.

Mukilteo completed its first major annexation in November 1980, adding 2,500 people living on 2 square miles (5.2 km2) to the south along State Route 525. This annexation nearly tripled the city's population and doubled its land area. Additional annexations and natural growth by the end of the decade brought the city's population to 6,000. The annexation of the large Harbour Pointe community was completed in 1991 and doubled the city's size to 6.6 square miles (17.09 km2). A competing proposal had sought to incorporate the planned community into a new city of 24,000 people, tentatively named Highland Bay, but residents supported annexation as a mutually agreeable option to reduce their taxes and benefit from city services. The annexation was also influenced by the county government's plans to allow passenger flights from Paine Field, which residents in Mukilteo and Harbour Pointe opposed alongside other nearby cities. The county ultimately withdrew their proposal to introduce passenger flights.

Several parties that opposed the annexation, including the county fire district, withdrew their complaints and allowed Mukilteo to annex Harbour Pointe on March 26, 1991. The annexation added 4,779 residents and 3.4 square miles (8.8 km2) to Mukilteo, doubling the city's population to 6,662 and size to 6.6 square miles (17 km2). It required the construction of two new fire stations, three schools, and a new city hall to house new employees. Kamiak High School was built in the Harbour Pointe area and opened in 1993 to serve Mukilteo, which had outgrown Mariner High School, and featured a technology-oriented curriculum. The full build-out of Harbour Pointe increased the city's population to over 18,000 by 2000, a 1,164 percent increase from 1980. The geographic and commercial center of Mukilteo was shifted further south towards Harbour Pointe, leading to cultural clashes with residents of older neighborhoods.

21st century

An agreement to transfer ownership of the Mukilteo Lighthouse from the U.S. Coast Guard to the city government was signed in 1999 after a decade of partial use as a museum by the local historical society. The changeover was made on August 19, 2001, with the Coast Guard retaining use of the working lights and the city government planning rehabilitation work to support the building's use as a tourist landmark. The adjacent Mukilteo State Park was transferred to the city government in February 2003, following an offer from the Washington State Parks and Recreation Commission to donate the park in order to stave off a budget shortfall. The new city park, named Mukilteo Lighthouse Park, underwent $6.6 million in renovations that were completed in 2008 to add a playground and other park amenities.

The 22-acre (8.9 ha) decommissioned fuel storage tank complex on the city's waterfront was identified for potential redevelopment in the 1990s, including use for a new ferry terminal. The Port of Everett led environmental cleanup of the site and constructed a new pier to transport large airplane sections for the Boeing 787 project, replacing the existing pier. The cleanup was completed in late 2006 after several delays due to the discovery of Indian artifacts that triggered an archaeological investigation. The existing pier was demolished in 2015 to make way for the new ferry terminal, which opened on December 29, 2020. The new terminal includes connections to an adjacent commuter rail station, which opened in 2008 and was expanded in 2016 by Sound Transit.

A research station for the Northwest Fisheries Science Center (part of NOAA) on the tank farm site was closed in 2020 and planned to be demolished in 2020 until the onset of the COVID-19 pandemic halted work. A project to build a new facility by 2022 was cancelled in March 2021 after NOAA received no bids below $40 million, which had been appropriated by the U.S. Congress; ownership of the property is expected to revert to the Port of Everett, which NOAA took over ownership from in 2001. The city government and Port of Everett has long-term plans to redevelop 26 acres (11 ha) of space around the old ferry terminal and NOAA facility into a walkable neighborhood with a waterfront promenade and trails.

On July 30, 2016, a mass shooting occurred at a house party in the Chennault Beach neighborhood of Mukilteo, around midnight. Three people were killed using an AR-15 style rifle and another was left with serious injuries. The perpetrator, a graduate of Kamiak High School, was sentenced to life imprisonment without the possibility of parole. The Mukilteo shooting—along with other high-profile mass shootings during the 2010s—was cited as the inspiration for an assault weapons restriction that was rejected by the state legislature and passed by voters in 2018 as Initiative 1639. In February 2018, an Everett resident was arrested prior to a planned school shooting that would have targeted ACES Alternative High or Kamiak High School.

The city annexed an 84-acre (34 ha) section of land south of Paine Field between Mukilteo Speedway and Beverly Park Road on July 16, 2025, citing its close proximity to city services.