The Plains

Head east out of Boulder on 63rd Street or the Diagonal Highway and the mountains stop being something you look up at. They become something you look back at: small, blue, and a little unreal along the horizon, while the land ahead flattens into farm fields and open space reaching toward Gunbarrel, Niwot, and Longmont. There are fewer houses out here and a lot more sky.

Boulder Reservoir anchors the area, a roughly 700-acre lake off 51st Street that the city runs as a swim beach and sailing center. The designated swim area typically opens at 10 a.m. and closes at 6 p.m., except Thursdays, when it closes early for weekly Stroke & Stride events. Community Sailing of Colorado teaches lessons right off the beach. A short drive north sits Boulder Municipal Airport, which opened in 1928 and is Colorado's oldest operating public airport, still mostly small planes and flight instruction rather than anything commercial.

Between the reservoir and the towns further out, most of the land stays protected open space or working farmland, crossed by quiet county roads that road cyclists have claimed as their own. The LoBo Trail runs twelve miles of crushed stone from Boulder through Gunbarrel and Niwot up to Longmont, passing close enough to the reservoir that you can sometimes hear the sailboats. Head the other way and the Coal Creek Trail picks up a similarly flat, wide-open ride through Superior, Louisville, Lafayette, and Erie.

Housing is sparse: a scattering of acreages, older farmhouses, and county land, with newer development creeping in from Gunbarrel and Erie at the edges. This part of Boulder is not walkable. You need a car, and bus service thins out fast once you are past Gunbarrel. It suits road cyclists, birders, sailors, and anyone who would rather look at the Flatirons from a distance than live underneath them.

East of Broadway and north of Valmont, the land opens up fast. Fields worked by tenant farmers border two-acre lots with a barn out back, a cluster of solar panels, and a truck parked at an angle that says nobody's coming by uninvited. Most of what's out here sits in the stretch between the Boulder Reservoir and the county line toward Niwot: county roads with no curb, a scatter of ranch houses from the 1970s next to newer builds on well and septic, and enough distance between mailboxes that trick-or-treating means driving between houses. Neighbors tend to be people who wanted acreage more than a walkable downtown: retired ranchers, commuters who work in Denver or at the labs in Boulder proper, and a handful of pilots who keep a plane at the municipal airport a few miles up the road.

Quiet is the main selling point, and it holds up most of the year, except on hot July weekends when the reservoir's parking lot fills by mid-morning and boat trailers line Jay Road. Small planes buzz overhead on practice patterns, more of a background hum than a nuisance once you get used to it. Winter turns the gravel roads to washboard ice, and a stiff wind off the plains can rattle a fence for days at a stretch. The tradeoffs are real: no sidewalks, no corner store, a fifteen-minute drive for groceries, and county plows that reach these roads later than the city ones do. What you get instead is a genuinely dark sky, deer in the yard most mornings, and enough space that the nearest neighbor's dog barking never quite reaches your porch.

Getting anywhere from here means driving, and most county roads feed onto the Diagonal Highway (CO 119), the fastest route into Boulder or up to Longmont. RTD's BOLT bus runs that corridor daily, about every half hour on weekdays, with a stop in Niwot, though the Niwot Park-n-Ride is closed for CO 119 Bus Rapid Transit construction and won't reopen with its expanded lot until 2027. Closer to Gunbarrel, Route 205 connects the Jay Road and reservoir turnoff to downtown Boulder, but it's a bus you plan a trip around, not one you catch on a whim. Cyclists get a better deal: the LoBo Trail runs mostly flat between Boulder and Longmont through Niwot and Gunbarrel. At the reservoir itself, plan on a paid day-use pass and a real parking lot rather than roadside parking.