Denver metro · County guide
Arapahoe County
The county Denver was carved out of: 805 square miles running 72 miles east, from the Tech Center to dryland wheat.
Where it is
Arapahoe County is the southeast quadrant of the Denver metro area plus a long band of high plains running out behind it. It begins at Sheridan Boulevard, the west edge of Denver, and reaches about 72 miles east to the Washington County line, but it is only about 12 miles deep from north to south. The western dozen miles hold nearly all the population and the rest is section-line ranch and farm country along Interstate 70.
Denver and Adams counties lie to the north, Jefferson to the west, Douglas and Elbert to the south, Washington to the east, and Lincoln meets it at the southeast corner.
- From downtown Denver
- 10 minutes to Glendale, half an hour to the Tech Center, about an hour to Deer Trail on the plains
- Elevation
- No foothills here: the county stops at Sheridan Boulevard, well east of the mountain front. USGS elevation queries put the ground near 5,460 feet at the Littleton Museum on the South Platte side, about 5,830 feet on the high ground at Centennial Airport, and about 5,180 feet at Deer Trail out east.
What makes it different
Six things that are true here and not one county over.
Colorado's first county, cut down
Almost half of what is now Colorado was Arapahoe County of Kansas Territory. When Colorado Territory organized its 17 original counties in 1861, Arapahoe was among them: a band 30 miles deep running roughly 160 miles from present-day Sheridan Boulevard east to the Kansas line, with Denver as its seat. In November 1902 the legislature broke it apart into the consolidated City and County of Denver, a new Adams County north of Colfax Avenue, and a remainder briefly called South Arapahoe County, which took the old name back in 1903. Littleton served as temporary seat until voters confirmed it over Englewood in 1904 by 1,310 to 829.
Twelve miles deep, seventy-two long
Census boundary files put the county at about 805 square miles, 798 of that land. It runs from Sheridan Boulevard out to roughly the Washington County line, some 72 miles, but measures only about 12 miles from the Adams County line south to County Line Road. That shape produces two different places. West of the E-470 corridor sit Aurora, Centennial, Littleton, Englewood, Greenwood Village, Sheridan, Glendale and Cherry Hills Village, thirteen municipalities in all. East of it the grid becomes section roads, dryland wheat and grazing along Interstate 70 and the Bijou and Kiowa creek drainages. The county's own published history describes three-fourths of its area as rural.
Cherry Creek Dam and the park
Castlewood Dam, upstream in Douglas County, failed in 1933 and sent a surge down Cherry Creek into Denver. Congress authorized a flood control structure downstream in the Flood Control Act of 1941, and the Army Corps of Engineers built Cherry Creek Dam between 1946 and 1950: an earthfill embankment roughly 141 feet high and 14,300 feet long. Colorado leased the land behind it in 1959 and opened Cherry Creek State Recreation Area, the first of its kind in the state. It is now Cherry Creek State Park, 4,227 acres wrapped around an 880-acre reservoir at 4201 South Parker Road, about 5,500 feet up, with 35 miles of trail and a 133-site campground.
Buckley and the old bombing range
The Army Air Corps used a stretch of prairie east of Denver as the Lowry bombing range and auxiliary field in the late 1930s. In spring 1942 it built a flight training school there. The second airfield went active that July and was renamed Buckley Field in June 1942 for First Lieutenant John Harold Buckley, a Longmont pilot killed in France in 1918. The installation is now Buckley Space Force Base, inside Aurora city limits and inside Arapahoe County. It is run by Space Base Delta 2 and hosts Space Delta 4, the Space Force's missile warning unit, along with the Colorado Air National Guard's 140th Wing.
The south metro office corridor
The Denver Technological Center started in 1962 on a 40-acre tract assembled by engineer George Wallace, who wanted an office campus with parking away from downtown. His holdings grew from 40 acres to more than 850 between 1962 and 1974, and the district now straddles Denver and Greenwood Village along Interstate 25. Centennial Airport sits a few miles southeast, owned by the Arapahoe County Public Airport Authority at 7565 South Peoria Street in Englewood, and the county calls it one of the busiest general aviation airports in the nation. Fiddler's Green Amphitheatre and the Greenwood Plaza offices anchor the north end of the same corridor.
Centennial, a city since 2001
Much of the county between Arapahoe Road and County Line Road sat unincorporated into the 1990s, covered by the Castlewood and Southglenn census designated places and served directly by county government. Residents organized in 2000 to gain local control and head off annexation by Greenwood Village. House Bill 1099 gave large incorporations priority over competing annexations, a district judge ruled for incorporation, Greenwood Village appealed, and the Colorado Supreme Court upheld the ruling. The City of Centennial was formed in 2001. A large unincorporated area remains, and county planners report its housing stock has a median year built of 1998, newer than the county overall.
How it got here
- 1848-1861
Prospectors bound for California panned Dry Creek where it enters the South Platte just west of present-day Englewood. The county's own published history calls this the first important gold discovery in Colorado and records the names Placer Camp and the Mexican Diggings. The Russell party found more gold downstream where the Platte meets Cherry Creek, founding the camp that became Denver, the county seat until 1902.
- 1859-1865
The Leavenworth and Pikes Peak Express brought the first stagecoaches into Denver in May 1859. Butterfield's Overland Despatch reached Denver in September 1865 by the new Smoky Hill Route, which crossed these plains. Mile houses stood every two or three miles along the Cherokee and Smoky Hill trails, each named for its distance from the corner of Colfax Avenue and Broadway in Denver.
- 1866-1872
The log core of the 17 Mile House went up around 1866 on the trail route, with Mary Hightower on the land under a military warrant. Richard Sullivan Little, an engineer from New Hampshire, homesteaded on the South Platte, and the Rough and Ready Flour Mill opened in 1867 to grind wheat for the mountain camps. The Denver and Rio Grande arrived in 1871 and Little platted the Village of Littleton in 1872.
- 1869
On July 4, 1869, ranch hands staged a bronco busting contest at Deer Trail. Horses had to be ridden with a slick saddle, stirrups untied and no spurs. A rider named Gardenshire of the Mill Iron ranch drew a bay called Montana Blizzard from the Hashknife outfit, stayed on for fifteen minutes, and took the title Champion Bronco Buster of the Plains and a suit of clothes. The account ran in Denver Field and Farm in 1899 and History Colorado reprinted it in 1951.
- 1870-1889
The Kansas Pacific Railroad, later the Union Pacific, was built west across the plains to Denver in the 1870s along roughly the old stage trail. It put a station at Deer Trail and platted that town in 1875. Bijou, founded in 1870 around a general store, gave way in May 1889 to Byers, laid out by Leonard McDonnell and John L. Fitzer and named for William N. Byers, editor of the Rocky Mountain News.
- 1891-1907
Denver developer Donald Fletcher incorporated the town of Fletcher on April 30, 1891, four square miles holding 21 houses, four businesses, one hotel and 36 voters. Water bonds sold that summer went bad and lawsuits followed. After Fletcher left, the town renamed itself Aurora on February 25, 1907. It reached city status with a census count of 2,295 in 1930 and stood at 11,421 by 1950.
- 1902-1904
Colorado voters ratified home rule for Denver in November 1902 and Governor Orman signed it into law on December 1, 1902. The act split what was left of Arapahoe County into Adams County and Arapahoe County with Colfax Avenue as the dividing line. Littleton served as temporary county seat until an election on November 8, 1904 chose it over Englewood, 1,310 to 829.
- 1946-1990
The Army Corps of Engineers finished Cherry Creek Dam in 1950 and the state opened the recreation area behind it in 1959. Aurora completed Quincy Reservoir in 1973 and finished construction on the Aurora Reservoir in 1989, filling it the following year and opening it to the public in 1991. Interstate 70 across the eastern plains was completed in 1972 and Interstate 225 was finished on May 21, 1976.
- 1962-2001
George Wallace opened the Denver Technological Center on 40 acres in 1962, and the south metro office corridor grew along Interstate 25 behind it. Fitzsimons Army Medical Center, just over the Adams County line in Aurora, wound down in 1997 and deactivated on June 30, 1999. The 17 Mile House was listed on the National Register in 1983; Arapahoe County bought it in 2001, the same year Centennial incorporated.
The towns inside it
What the housing looks like
The oldest stock stands along the South Platte on the western edge. Historic downtown Littleton keeps late 1800s brick commercial fronts on Main Street with frame Victorian houses and early bungalows on the small blocks behind them, and Englewood carries a similar prewar layer of bungalows and square-plan frame houses on a tight grid off South Broadway. Almost everything else is postwar. The 1950s and 1960s produced brick ranches on quarter-acre lots through central Englewood, Sheridan, western Aurora along East Colfax and Sixth Avenue, and the older Littleton subdivisions: single story, low pitched roof, attached one-car garage, brick veneer with wood or aluminum trim. Cherry Hills Village and Bow Mar platted as large-lot districts, Bow Mar on roughly one-acre lots across 520 acres, so those streets read as lanes rather than blocks. The 1970s and 1980s filled Centennial's Southglenn and Castlewood areas and southeast Aurora with two-story frame tract houses on curvilinear plats built around cul-de-sacs. From the 1990s on, the growth line moved east past E-470 into Aurora's reservoir subdivisions and newer Centennial platting: stucco and stone veneer, three-car garages, plated roof trusses, streets organized around detention ponds and trail corridors. The county counted 275,293 housing units in 2024, 55 percent in single-unit structures and 44 percent in multi-unit buildings, with 15 percent of all units built since 2010. Out east, houses sit on well and septic on section-line acreage.
The events board
Community events that come back every year. Each card links to the organiser for this year's exact date.
17 Mile House Farm Park Open House
One Saturday a month from mid-spring into late autumn, usually toward the end of the month. The season opens in April.
17 Mile House Farm Park, 8181 S. Parker Rd., Centennial
Arapahoe County opens the buildings at its 1860s stage stop on the old Cherokee and Smoky Hill trail route, the only mile house in the region still standing in a rural setting on its original site. The grounds are open dawn to dusk year round, but the farmhouse, red barn, brick silo, milk house and loafing shed stay shut except on these days. Each open house carries a theme run with partner groups: past subjects include site archaeology, pollinator gardening, a 4-H expo and traditional weaving. The park is also a trailhead for the Cherry Creek Regional Trail.
Colorado Remembers
The Saturday of Memorial Day weekend, morning through early afternoon.
Colorado Freedom Memorial, 756 Telluride St., Aurora
The city of Aurora and the Colorado Freedom Memorial Foundation open the memorial for a remembrance ceremony, a free-will donation pancake breakfast and a static display of military vehicles and artifacts. The memorial is a wall of glass panels etched with the names of Coloradans killed or missing in action, and guided tours of it follow the ceremony. Past displays have included the Honor Bell and a steel beam from the USS Arizona. Bags are inspected at the gate. No glass bottles, no outside alcohol, and no animals other than service animals.
Live Racing Season at Bally's Arapahoe Park
The meet opens in mid-June and runs Fridays, Saturdays and Sundays into mid-August.
Bally's Arapahoe Park, 26000 E. Quincy Ave., Aurora
The only track in Colorado running live pari-mutuel horse racing. The seasonal meet cards Thoroughbred, Quarter Horse and Arabian races with a 1 p.m. post time on race days, and the building carries simulcast wagering from other tracks year round. General admission runs a few dollars on Saturdays and Sundays and nothing on Fridays. Anyone 17 and under enters at no charge with a parent, seniors pay a nominal rate, and the minimum age to place a wager is 18. The grandstand sits on the far eastern edge of Aurora with open prairie behind it.
Arapahoe County Fair
The last weekend of July, Thursday through Sunday.
Arapahoe County Fairgrounds, 25690 E. Quincy Ave., Aurora
The county's longest-running public event. It was first held in 1906 along the South Platte in what is now Littleton and moved among Deer Trail, Byers, Englewood and Littleton over the years before settling at the Quincy Avenue fairgrounds. One gate ticket covers unlimited carnival rides, daily motor sports, a rodeo, a petting farm and grandstand entertainment, with 4-H and FFA livestock barns and open exhibits alongside. Saturday is the heaviest day and the gates and parking lots can close once the grounds fill. It runs rain or shine, and refunds are not issued for weather or capacity closures.
Western Welcome Week
Ten days starting on a Friday in early August and closing the following Sunday.
Greater Littleton, most of it in and around historic downtown Littleton. The organizing nonprofit is at 5890 South Bemis Street.
Ten days and more than 30 separate events, run by an independent nonprofit rather than by the city. It grew out of a July 1928 anniversary party thrown by the editor of the Littleton Independent, became an annual Homecoming in 1929 built around the hundredth birthday of town founder Richard S. Little, and was renamed Western Welcome Week in 1962. The lineup includes the Grand Parade with a named grand marshal, a maker and crafter fair, art shows, gold panning on the South Platte, a pancake breakfast and a duck race. Most of it costs nothing to attend.
RugbyTown 7s
Three days over a weekend in the second half of August, Friday through Sunday.
Infinity Park, 4599 East Tennessee Ave., Glendale
Glendale opened the Infinity Park complex in 2007, built around a city-owned rugby stadium with an event center, sports center and open space around it. The sevens tournament brings international and domestic sides, including armed forces teams, for three days of seven-a-side matches, dozens of games a day on one pitch, with a beer and food festival running on the concourse alongside. Tickets are sold by the day or as a tournament pass, and gates open late morning each day. Glendale is a 0.6-square-mile city ringed entirely by Denver, so the stadium sits mid-metro rather than out on the edge.
Littleton Museum Harvest Festival
The second Saturday of October, late morning to mid-afternoon.
Littleton Museum, 6028 S. Gallup St., Littleton
The Littleton Museum keeps two working living history farms on its grounds, one set in the 1860s and one in the 1890s, with costumed interpreters, a blacksmith shop and livestock. For the harvest festival the farms open for pumpkin picking, hay and wagon rides, 1890s carnival games and period demonstrations, and some of the pumpkins are grown on site. Museum admission is free year round and the festival gate costs nothing, though pumpkins and certain activities are paid for with tickets bought on the day. Proceeds go to library and museum programming.
Candlelight Walk
The Friday evening after Thanksgiving.
Historic downtown Littleton, centered on West Main Street
Downtown Littleton's holiday opener and the biggest night of the year on Main Street. Performers and holiday music fill the sidewalks, a parade runs through downtown, hot cocoa and warm cider are handed out at no charge, and there are photo stops with Santa along the route. The evening now closes with a drone show over downtown. Shops and restaurants stay open through it, and parade applications open to local groups in the summer. Attending costs nothing.
Aurora Holiday Tree Lighting
A weekday evening in early December, about two hours after dark.
Aurora Municipal Center, 15151 E. Alameda Parkway, Aurora
The city switches on thousands of strands of lights across the municipal center campus. The evening carries holiday activities, sweet treats, dance performances and Santa, and the Merry Makers Market runs at the same time inside the neighboring Aurora Central Library as a vendor market for holiday shopping. Parking on site is free across three lots at the municipal center, and the R Line light rail stops at the Aurora Metro Station within a short walk. Bags are inspected. No glass bottles, no outside alcohol, and no animals other than service animals.
Checked 2026-08-03 against county and city sources: files.arapahoeco.gov · arapahoeco.gov · arapahoeco.gov · files.arapahoeco.gov · files.arapahoeco.gov · files.arapahoeco.gov · files.arapahoeco.gov · historycolorado.org · historycolorado.org · cdnsm5-hosted.civiclive.com · cpw.state.co.us · auroragov.org · auroragov.org · auroragov.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.
Thinking about Arapahoe County?
A house off Broadway in Englewood and a house past E-470 are the same county and nothing else alike. I can tell you which one you are looking at.
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