Denver, Colorado in the Northern Front Range of the Rocky Mountains is a nonattainment area for ground-level ozone. In addition to local precursor emissions such as heavy motor vehicle usage and an active oil and natural gas industry, summertime ozone levels in this area are further influenced by western U.S. wildfires as well as complex flow patterns related to the elevated terrain and diurnal mountain-valley winds. Numerous studies have investigated air quality in the Denver basin, and the persistent high levels of summertime ozone emphasize the ongoing need for monitoring and mitigation for the protection of public health. In summer 2017, the Colorado Department of Public Health & Environment measured hourly ozone at seven sites along a vertical transect on the eastern slope of the Rocky Mountains, from Golden, CO (1839m ASL, 39.743°N, 105.179°W) to Mines Peak (3683m ASL, 39.794°N, 105.764°W) to determine the vertical extent and temporal variability of the Denver ozone plume. Hourly temperature, wind speed and direction were measured at five of the sites. Mean ozone increased by 1.0 ppb per 100m for the four lowest elevation sites (up to Black Hawk, 2627m ASL), which is a smaller slope than was determined in a previous vertical transect in the Northern Front Range as well as in vertical gradients at more rural mountainous sites. At these same four sites, diurnal amplitudes in hourly mean ozone generally decreased with increasing elevation, from 26 ppb to 13 ppb, and the effects of katabatic mountain wind patterns on diurnal ozone levels were evident. In contrast, two higher elevation sites, Jim Creek (3104 m ASL) and St Mary (3163 m ASL), showed weaker associations with katabatic wind patterns, significantly lower mean ozone concentrations than adjacent lower elevation sites, and larger ranges in hourly concentrations across the sampling period. However, Jim Creek was also situated in a different airshed and on the upwind side of Continental Divide so as to examine possible spill-over of Denver air masses, which occurred infrequently but resulted in elevated ozone levels when it did. Mines Peak appeared to serve as a regional background site, with little influence from daytime photochemical production or nighttime depositional losses. An identified regional fire event in early September 2017, resulting in a high ozone episode, was assessed using a combination of local criteria pollutant measurements, satellite imagery, and air mass back-trajectories.