The Town of Danville is located in the San Ramon Valley in Contra Costa County, California, United States. It is one of the incorporated municipalities in California that use "town" in their names instead of "city". The population was 43,582 at the 2020 census. Since 2018, for five consecutive years, Danville was named "the safest town in California".

The Iron Horse Regional Trail runs through Danville. It was first a railroad that has been converted to an 80-foot-wide (24 m)[citation needed] corridor of bike and hike trails as well as controlled intersections. Extending from Livermore to Concord, the trail passes through Danville.

Danville is also home to the Eugene O'Neill National Historic Site, Village Theatre and Art Gallery, and the Museum of the San Ramon Valley.

Often referred to as the "Heart of the San Ramon Valley", Danville was first populated by Native Americans who lived near creeks and camped on Mount Diablo in the summer. Later, it was part of Mission San José's grazing land as well as a Mexican land grant called Rancho San Ramon.

Initially a farming community, the Town of Danville switched from wheat to fruits and nuts after the Southern Pacific Railroad built a spur line through the area in 1891. It developed as a residential suburb in 1947 when the first sizable housing tracts were constructed and its population boomed in the 1970s and 1980s.

The Danville Post Office opened in 1860 with hotel owner Henry W. Harris as the first postmaster.

Churches, schools, farmers unions and fraternal lodges began as the community grew. The Union Academy, a private high school begun by the Cumberland Presbyterian Church, served the county from 1859 to 1868, until it burned down. Danville Presbyterian Church was dedicated in 1875.

Many early Danville buildings remain standing today. The original 1874 Grange Hall exists as well, and the original Danville Hotel remains downtown which was last renovated in 2016. Many of the early pioneer names appear on the streets and schools, including Baldwin, Harlan, Wood, Love, Hemme, Boone, Bettencourt and Meese.

When the Southern Pacific Railroad came to the Valley in 1891, Danville continued to grow. Farmers built warehouses and shipped crops by rail, and residents were able to travel to and from Danville.

John Hartz sold 8.65 acres (3.50 ha) of his land for the Danville Depot and granted land access to the station. He then subdivided and sold lots east of the station, shifting the town's focus from Front Street to Hartz Avenue. Eventually, a bank, drug store, saloon, doctor's office and Chinese laundry joined the houses lining the street. The Danville Hotel originally sat across from the station and was moved to face Hartz avenue in 1927.

The twentieth century found Danville affected by the wars, the Spanish flu, the depression, and new immigrants.

In 1910, a public high school district was organized and San Ramon Valley Union High School was built. A library opened in 1913 with 104 books. St. Isidore's Catholic Church was first established in 1910. An Improvement League funded the first streetlights and paved roads in 1915.

Danville continued as farm country into the 1940s. The Valley had a population of 2,120 people in 1940, growing to 4,630 by 1950. Developments such as Montair and Cameo Acres were built, the water and sewer districts extended their boundaries, and the new I-680 freeway which cut through Danville in the mid-1960.

In 1982, Danville citizens voted to incorporate their community.

In 2000, Danville's population reached 40,484.

Danville was ranked as the safest city in California for a fifth consecutive year, most recently in 2022.

Danville is set in a narrow section of the San Ramon Valley with the Las Trampas Ridge to the west and the Diablo Range to the east. The most prominent landmark of Danville is the backdrop of Mount Diablo, which stands to the east at 3,849 feet (1,173 m) and provides a picturesque backdrop for Danville and neighboring towns and cities. Sycamore Creek drains some of the Mount Diablo slopes and flows through Danville.

To the north of Danville, the unincorporated town of Alamo sits in the uppermost reaches of the San Ramon Valley and extends into the surrounding hills. San Ramon, another affluent suburb, borders Danville to the south.

Interstate 680, extending along the valley to the north and south, is the main route used by traffic in and out of town. Camino Tassajara is the main thoroughfare for east–west travel, most importantly to reach the eastern subdivisions far from the interstate. Camino Tassajara also provides access to the wealthy gated community of Blackhawk.

According to the United States Census Bureau, the town has a total area of 18.0 square miles (47 km2), all of it land.

Danville's weather typifies a Mediterranean climate. Summers are long, with hot days and cool nights. Winters are cool, with mild daytime temperatures usually in the 50s, and nighttime temperatures usually above freezing. Like in the rest of the Bay Area, summers in Danville are extremely dry, and it's not uncommon for four to six months to elapse between the last drop of rain in the spring and the first rain in the fall. Winters are rainy, but periods of several days to a week of mild, dry, sunny weather are quite common even in midwinter.

According to Business Insider, Danville's 94506 is the 14th wealthiest ZIP code in America. Danville is one of the wealthiest suburbs of Oakland and San Francisco. Danville also ranks as the 2nd highest-income place in the United States with a population of at least 40,000. It is home to some of the most expensive real estate in the San Francisco Bay Area and the United States. According to CNN Money, Danville's 94506 also has the fourth highest percentage of six-figure income earners in the nation, with 78% of Danville households having at least a six-figure income.

The 2010 United States Census reported that Danville had a population of 42,039. The population density was 2,331.9 inhabitants per square mile (900.4/km2). The racial makeup of Danville was 34,942 (83.1%) White, 372 (0.9%) African American, 67 (0.2%) Native American, 4,417 (10.5%) Asian, 68 (0.2%) Pacific Islander, 509 (1.2%) from other races, and 1,664 (4.0%) from two or more races. Hispanic or Latino of any race were 2,879 persons (6.8%).

The Census reported that 41,796 people (99.4% of the population) lived in households, 56 (0.1%) lived in non-institutionalized group quarters, and 187 (0.4%) were institutionalized.

There were 15,420 households, out of which 6,034 (39.1%) had children under the age of 18 living in them, 10,389 (67.4%) were opposite-sex married couples living together, 1,140 (7.4%) had a female householder with no husband present, 449 (2.9%) had a male householder with no wife present. There were 452 (2.9%) unmarried opposite-sex partnerships, and 84 (0.5%) same-sex married couples or partnerships. 2,801 households (18.2%) were made up of individuals, and 1,365 (8.9%) had someone living alone who was 65 years of age or older. The average household size was 2.71. There were 11,978 families (77.7% of all households); the average family size was 3.10.

The population was spread out, with 11,196 people (26.6%) under the age of 18, 2,117 people (5.0%) aged 18 to 24, 8,050 people (19.1%) aged 25 to 44, 14,628 people (34.8%) aged 45 to 64, and 6,048 people (14.4%) who were 65 years of age or older. The median age was 44.5 years. For every 100 females, there were 93.5 males. For every 100 females age 18 and over, there were 90.3 males.

There were 15,934 housing units at an average density of 883.8 units per square mile (341.2 units/km2), of which 15,420 were occupied, of which 13,020 (84.4%) were owner-occupied, and 2,400 (15.6%) were occupied by renters. The homeowner vacancy rate was 0.8%; the rental vacancy rate was 5.3%. 36,137 people (86.0% of the population) lived in owner-occupied housing units and 5,659 people (13.5%) lived in rental housing units.

The Danville Library of the Contra Costa County Library is located in Danville. It is one of the busiest libraries in Contra Costa County by circulation.

According to the California Secretary of State, as of February 10, 2019, Danville has 30,076 registered voters. Of those, 10,412 (34.6%) are registered Democrats, 10,381 (34.5%) are registered Republicans, and 7,963 (26.5%) have declined to state a political party.

Throughout its history until 2008, Danville was a Republican stronghold in presidential elections. Ronald Reagan carried it by a 3-to-1 margin in 1984. However, in 2008, Barack Obama became the first Democrat to carry Danville in a presidential election. He narrowly won it again in 2012 with a plurality. Hillary Clinton carried it in 2016 by nearly 24 points and Joe Biden won it by nearly 29 points in 2020.

The Town of Danville has a Council–manager government, with a five-person Town Council and an appointed Town Manager. Council members' terms are four years. Each year, in December, the council selects a new mayor to take office in January. The current mayor of Danville is Karen Stepper.

Danville has its own police department, which consists of 42 full-time employees, including 30 Officers and 12 civilian support staff. In addition, it has 8 Reserve officers and 32 volunteers. Allan Shields is the current police chief.

The San Ramon Valley Fire Protection District (SRVFPD) provides fire protection for Danville. A Special District, it covers 155 square miles includes the following communities: Alamo, Blackhawk, Diablo, the City of San Ramon, the southern boundary of Morgan Territory and the Tassajara Valley, all located in Contra Costa County.