Denver metro · County guide
Boulder County
The Front Range county that bought its own backdrop: 108,000 protected acres, a university, and federal science labs.
Where it is
Boulder County occupies the northwest corner of the Denver metro area and reaches west to the Continental Divide. About a third of the county is plains east of the foothills, and the rest climbs through the foothills to the Divide.
Larimer County to the north, Weld County to the east, Broomfield to the southeast, Jefferson and Gilpin counties to the south, and Grand County to the west across the Continental Divide.
- From downtown Denver
- 25 to 50 minutes northwest, US 36
- Elevation
- Just under 5,000 feet on the eastern plains up to Longs Peak, a fourteener and the county high point, inside Rocky Mountain National Park. The foothills break out of the plains abruptly west of Boulder, so grade and snowfall change within a few miles, and the winter downslope windstorms that funnel off that wall are what drove the Marshall Fire.
What makes it different
Six things that are true here and not one county over.
The Blue Line and the tax
In 1959 Boulder voters amended the city charter to bar city water service above 5,750 feet, which stopped foothill subdivision before it started. In 1967 the city passed a 0.40 cent sales tax to buy open space, the first US city to tax itself for that purpose, approved with 57 percent support. Boulder Open Space and Mountain Parks now manages more than 46,640 acres, and Boulder County protects another 108,082 acres, of which 40,872 are private land under conservation easement.
The 6,000 square foot ceiling
In unincorporated Boulder County, any residence whose total floor area passes 6,000 square feet, counting garages, basements and accessory structures, requires the purchase of Transferable Development Credits before a building permit issues. The scale steps up: one credit for the first 500 square feet over the threshold, one for the second, then two credits per 500 after that. Credits trade privately or through a county clearinghouse, and sellers must report sale prices within five business days, so the pricing is public.
Old coal workings under the southeast
Louisville, Lafayette, Erie and parts of Superior sit above room and pillar coal mines of the Northern Coal Field, with mapped workings ranging from roughly 50 feet to more than 400 feet down. Those mines were built to collapse, and subsidence is excluded from standard homeowner policies, so Colorado runs a separate Mine Subsidence Protection Program covering residential structures built before February 22, 1989 over mines that closed before 1977. Pulling the undermining maps is routine due diligence in those towns.
Colorado water law starts here
Coffin v. Left Hand Ditch Co., decided by the Colorado Supreme Court in 1882, arose from a dam on the St. Vrain that moved water into James Creek and then Left Hand Creek. A downstream landowner tore out part of the dam, lost the case, and the ruling established prior appropriation, first in time first in right, as the Colorado Doctrine now followed across the arid West. Left Hand Creek carries the name of Chief Niwot, the Arapaho leader whose name means left hand.
Federal science campus on Broadway
The Department of Commerce Boulder Laboratories at 325 Broadway began construction in 1951 and were dedicated by President Eisenhower on September 14, 1954. They house NIST, NOAA and NTIA, with NCAR's Mesa Laboratory on the bench above Table Mesa. The University of Colorado was established at Boulder in 1876, and IBM announced its plant between Boulder and Longmont in 1965.
The 55 foot height limit
A 1971 charter amendment capped building height in Boulder at 55 feet, and most zones hold to 35 feet with modifications available up to that ceiling. The separate residential growth cap, descended from the 1976 Danish Plan and later set at 1 percent a year, was repealed by City Council in January 2024 to comply with a 2023 state law. It had carried so many exemptions that city staff said it had not constrained residential permits for at least two decades.
How it got here
- 1858-1859
A party led by Thomas Aikins camped at the mouth of Boulder Canyon on October 17, 1858, and gold was struck at Gold Run on January 16, 1859. Boulder City was laid out the following month, and Gold Hill was founded about ten miles up the canyon.
- 1861
Boulder County was created in November 1861 as one of the original counties of Colorado Territory, with Boulder as the county seat. Silver followed at Caribou in 1869 and gold telluride at Gold Hill in 1872.
- 1871-1903
The Chicago-Colorado Colony platted Longmont in 1871 on a one square mile grid with stores along Main Street and three parks, and irrigation turned the plains to wheat and sugar beets. Coal came out of Marshall, Louisville, Lafayette and Erie, Edward Lyon opened commercial sandstone quarries in 1880, and Great Western Sugar built its Longmont factory in 1903.
- 1952-1965
The Denver-Boulder Turnpike opened January 19, 1952 as a 17.3 mile toll road charging 25 cents, and its bonds were retired early so tolls came off in 1967. The federal Boulder Laboratories were dedicated in 1954, the FAA air traffic control center opened in Longmont in 1962, and IBM announced its plant in 1965.
- 1959-1978
Boulder drew the Blue Line in 1959, passed the open space sales tax in 1967, capped building height in 1971 and adopted the Danish Plan growth cap in 1976. Boulder County adopted its comprehensive plan in 1977 and 1978, and the city and county signed an intergovernmental agreement tying urban development and utility extensions to defined service areas, which is why the urban edge is still a hard line rather than a fade.
- 2001-2021
In 2001 the county lost 27.5 square miles of its southeastern corner to the new City and County of Broomfield. The September 2013 flood dropped more than 17 inches of rain, cut off Lyons and Jamestown and took out dozens of bridges, and the Marshall Fire on December 30, 2021 destroyed 1,109 homes in Louisville, Superior and unincorporated county.
The towns inside it
What the housing looks like
The oldest stock rings downtown Boulder: Victorian and Queen Anne houses on Mapleton Hill from the late 1800s, then Craftsman bungalows built roughly 1905 to 1930 through Whittier and University Hill, much of it trimmed in the local red Lyons sandstone that also faces the University of Colorado campus in Charles Klauder's rough-cut sandstone and red tile style. The southeastern coal towns of Louisville, Lafayette and Erie keep compact early 1900s cottages on tight grids near their original main streets, wrapped by postwar ranches and then large 1990s and 2000s subdivisions. Longmont still reads as its 1871 one square mile grid at the core, with brick and frame houses giving way to 1960s and 1970s ranches built out after the FAA center and IBM arrived. Superior is nearly all post-1987 Rock Creek construction plus Marshall Fire rebuilds, while the mountain half of the county is cabins, A-frames and custom houses on well and septic, capped at 6,000 square feet unless credits are purchased.
The events board
Community events that come back every year. Each card links to the organiser for this year's exact date.
Boulder County Farmers Markets
Saturdays from early April through late November. Boulder adds a Wednesday afternoon market from May through early October.
13th Street between Canyon and Arapahoe in Boulder, and the Boulder County Fairgrounds at 9595 Nelson Road in Longmont.
Growers-only markets, meaning vendors sell what they raised. Saturday mornings run into the early afternoon at both sites. There is a prepared food court for breakfast, live music from bluegrass to jazz, produce that turns over with the season, and Palisade peaches in late summer. SNAP/EBT and WIC are accepted for produce. Walking in costs nothing.
BolderBoulder 10K
Memorial Day, the last Monday in May.
Boulder. The course starts at 30th and Walnut and finishes inside the University of Colorado's Folsom Field.
A 10K through Boulder streets with a wave start that sorts entrants by pace, from professional runners down to walking waves, so people of any speed can enter together and walk the whole thing. Bands and neighborhood spectators line the route. It ends with the Memorial Day Tribute inside Folsom Field, which is open to the public. Entering the race costs money. Watching from the course does not.
Boulder Creek Festival
Memorial Day weekend, Friday evening through Monday afternoon.
Along Boulder Creek from 9th Street to 14th Street, between Canyon Boulevard and Arapahoe Avenue, Boulder.
More than 30 bands across three stages, and every concert is free. There are roughly 200 artisan booths, 30-plus food vendors, a Creekside for Kids area, and outdoor movie nights on the grass Saturday and Sunday. Bring blankets and lawn chairs. The only ticketed piece is the Creekside Beer Fest tasting.
Rock and Rails
Thursday evenings, early June through late August.
Whistle Stop Park, Niwot.
A free outdoor concert series next to the railroad tracks in Niwot. Happy hour and an opening act start the evening, then a headliner plays into the night. Food trucks, beer vendors, artisan booths and kids' activities fill the park. Bring portable chairs and blankets. Outside alcohol is not allowed, and no animals except service dogs.
Boulder County Fair
First full week of August, Wednesday through Sunday. The kickoff parade runs the Saturday before.
Boulder County Fairgrounds, 9595 Nelson Road, Longmont. The parade is in downtown Longmont.
Five days of 4-H and FFA livestock barns, a carnival midway, a petting zoo, the Kids' Corral, and open exhibits of baking, canning and needlework. There is free live music, a livestock show and rodeo, and fair food. Gate admission and parking both cost nothing, so you can come back more than once in the week.
Lafayette Peach Festival
A Saturday in August, 9 a.m. to 4 p.m.
Public Road through Old Town Lafayette.
The street closes for a festival built around Palisade peaches trucked in from the Western Slope by the ton. The reason to go is the peach pie, cobbler and hand pies sold by the slice, and boxes of peaches to take home. Craft, art and food vendor booths line Public Road, and there are inflatables for kids that carry a separate fee. The festival is free to the public and runs rain or shine.
Louisville Labor Day Parade and Fall Festival
Labor Day weekend. Senior Dinner Friday evening, then the pet parade, main parade and festival all on Labor Day Monday.
Downtown Louisville along Main Street, and Memory Square Park.
The Children's Pet Parade at 9 a.m. is open to kids 12 and under and runs south on Main Street. Past entries have included dogs, cats, a llama, stuffed animals and pet rocks. Every child gets a prize and a popsicle at the end. The Labor Day Parade follows at 10 a.m. from Lafayette and Main with marching bands, dance troupes and equestrians. The Fall Festival at Memory Square Park runs through the afternoon with craft and produce vendors, food trucks, and a pie contest.
Munchkin Masquerade
Halloween afternoon.
Pearl Street Mall and the East End and West End districts, downtown Boulder.
Daylight trick-or-treating for kids 12 and under. More than 70 downtown shops and restaurants sign up as Treat Stops and hand out candy along Pearl Street. There is a free coloring tent on the 1400 block and extra goodies at the Visitor Information Center. Produced by Downtown Boulder Community Initiatives at no charge.
Lights of December Parade
A Saturday evening in early to mid December.
Downtown Boulder. The route runs from 15th and Walnut west to Broadway, north on Broadway past a reviewing stand at Broadway and Pearl, then east on Spruce to 15th.
Floats built and lit by downtown businesses, churches, schools and civic groups, plus marchers and fully lit fire engines, moving through downtown after dark. Santa rides at the end of the procession. Watching from the sidewalk costs nothing. The reviewing stand at Broadway and Pearl has the best sightlines for kids.
Checked 2026-08-03 against county and city sources: stories.opengov.com · bouldercounty.gov · bouldercounty.gov · bouldercounty.gov · bouldercounty.gov · bouldercolorado.gov · longmontcolorado.gov · boulder.doc.gov · coloradogeologicalsurvey.org · coloradogeologicalsurvey.org · lafayetteco.gov · nist.gov · its.ntia.gov · boulderreportinglab.org. Event dates move a week either way from year to year, so each card links to the organiser rather than printing a date that will be wrong by next spring.
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The open space that makes it look like that is also what makes supply tight. I can tell you what that means for a specific street.
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