Walsenburg is the statutory city that is the county seat and the most populous municipality of Huerfano County, Colorado, United States. The city population was 3,049 at the 2020 census, down from 3,068 in 2010.

Walsenburg was originally settled under the name of La Plaza de los Leones in 1859. The settlement was named after settler Don Miguel Antonio de Leon, who came along with others from New Mexico. A post office called Walsenburg has been in operation since 1870. The community was named after Fred Walsen, an early settler. Robert Ford, the famous gunman, operated a combination saloon and gambling house in Walsenburg; his home at 320 West 7th Street still stands. The town is also remembered in sports history due to a famous newspaper gaffe ("Will Overhead") after the 1933 Indianapolis 500.

Walsenburg played a central role in the 1913-1914 Strike of the United Mine Workers of America against the Rockefeller-owned Colorado Fuel and Iron, an event better known as the Colorado Coalfield War. The town was the site of a Colorado and Southern Railway stop and location of several gun-battles before and after the April 20, 1914 Ludlow Massacre that killed over a dozen women and children when Colorado National Guard opened fire on a striker encampment at Ludlow, 22 miles south of Walsenburg. Among the first instances of violence in Walsenburg during the coal strikes is known as the Seventh Street Massacre, which saw three miners die in a shooting perpetrated by newly minted Walsenburg deputies.

The Battle of Walsenburg (April 28–29, 1914) was the penultimate engagement of National Guard and militia against pro-strikers during the 10-Day War stage of the conflict. Several men on both sides, as well as at least one uninvolved civilian, were killed before strikers withdrew.

Walsenburg is mentioned in the Woody Guthrie song "Ludlow Massacre".

In 1927 the coal mines in Walsenburg were one of the many shutdown during the statewide strike led by the IWW.

On June 19, 2013, Boy Scouts at Spanish Peaks Scout Ranch noticed an uncontrolled fire near East Spanish Peak which rapidly grew over the next few days, growing into the East Peak Fire. The entirety of Walsenburg was placed under a pre-evacuation notice. The fire burned 13,572 acres (54.92 km) and was contained on July 9.

Walsenburg is located in east-central Huerfano County, on the north side of the Cucharas River, at the eastern edge of the foothills of the Sangre de Cristo Mountains. Interstate 25 runs along the eastern edge of the city, with access from Exits 49, 50, and 52. I-25 leads north 48 miles (77 km) to Pueblo and south 36 miles (58 km) to Trinidad. U.S. Route 160 passes through the center of Walsenburg, leading west across North La Veta Pass 72 miles (116 km) to Alamosa and south with I-25 to Trinidad. Colorado State Highway 10 leads northeast from Walsenburg 73 miles (117 km) to La Junta.

According to the United States Census Bureau, Walsenburg has a total area of 3.2 square miles (8.2 km), all of it land.

The Spanish Peaks Regional Health Center is located 2 miles (3 km) west of Walsenburg on US 160, opposite the entrance to Lathrop State Park. The building houses a state-operated veterans' retirement home and a community hospital that serves the area.

Walsenburg has a humid subtropical climate (Cfa) with hot, rainy summers with cool nights and cool snowy winters with chilly nights.

Lathrop State Park, located 2 miles (3 km) west of the Walsenburg city limits, is Colorado's first state park and is over 1,600 acres (6.5 km) in size. Martin Lake and Horseshoe Lake offer fishing stocked by Colorado Parks and Wildlife, water skiing, boating, and jet skiing. Hiking and camping are other activities in the park, and it is the only state park in Colorado with a golf course.

The Spanish Peaks, 10 miles (16 km) southwest of Walsenburg are a national landmark and have been named one of "Colorado's Seven Wonders" by The Denver Post. The Highway of Legends, connecting Walsenburg with La Veta, other historic mining towns, and Trinidad, is a National Scenic Byway.

The Walsenburg Golf Course is a 9-hole public golf course open for play year round. The city opened a $2 million water park, "Walsenburg Wild Waters", after efforts by former mayor Maurice Brau and the City Council, on May 27, 2007.

Historical population

Census	Pop.	Note	%±
1880	377		—
1890	928		146.2%
1900	1,033		11.3%
1910	2,423		134.6%
1920	3,565		47.1%
1930	5,503		54.4%
1940	5,855		6.4%
1950	5,596		−4.4%
1960	5,071		−9.4%
1970	4,329		−14.6%
1980	3,945		−8.9%
1990	3,300		−16.3%
2000	4,182		26.7%
2010	3,068		−26.6%
2020	3,049		−0.6%
U.S. Decennial Census

John Mall High School is the local high school. It is the only high school in Huerfano District Re-1. In the 2021–2022 school year, there was a total enrollment of 137 students. 56% of the enrollment was male and 44% was female. There was a student-to-teacher ratio of 27:1, which is higher than the Colorado state average of 15:1. 66% of the student body identified as a minority, with most of them being Hispanic. The state average of minority enrollment is 48%. The graduation rate ranges from 70 to 79%, which is lower than the state average of 80%.

Greyhound Lines serves Walsenburg on its route between Denver and Albuquerque. Walsenburg is part of Colorado's Bustang network. It is on the Trinidad-Pueblo Outrider line.

Notable individuals who were born in or have lived in Walsenburg include:

• Xavier Atencio (1919–2017), animator
• Star Caywood (1915–1968), Colorado state representative
• Robert Ford (1861–1892), murderer, saloon owner
• Debora Greger (born 1949), poet
• Mary Harris "Mother Jones" (1837–1930), labor organizer
• Matthew G. Martínez (1929–2011), U.S. Representative from California
• Frank Olmstead, mayor of Las Vegas, New Mexico, and 18th Auditor of New Mexico
• John R. Petrus (1923–2013), Wisconsin state legislator
• Roy Porter (1923–1998), jazz drummer
• Sam T. Taylor (1903–1977), Colorado state senator
• Albert J. Tomsic (1925–2012), politician, attorney, and judge
• Fred Walsen (1841-1906), city founder and Colorado State Treasurer

• Huerfano County, Colorado

• City of Walsenburg official website
• CDOT map of the City of Walsenburg
• Walsenburg travel guide from Wikivoyage