Hourly averaged ozone (O3) measurements from 2005-2016 collected at the Manitou Springs station, Colorado, were analyzed to determine long-term trends and assess the ability for the Colorado Springs metropolitan area to be in attainment of the O3 National Ambient Air Quality Standards (NAAQS). The EPA recently lowered the NAAQS for O3 from 75 ppbv to 70 ppbv, posing attainment challenges for high elevation regions of the western United States, including Colorado Springs, due to the impacts of baseline O3. Baseline O3 is defined as O3 that is transported to a location from upwind sources. This study aims to identify possible causes of different O3 trends in Colorado Springs. The annual 99th percentile O3 concentration showed a significant decrease of -0.71 ppbv yr-1 (-0.96% ppbv yr-1), and the annual 5th percentile significantly increased by 0.81 ppbv yr-1 (5.8% ppbv yr-1), while the annual 50th and 95th percentiles did not show significant trends. The decreasing trends generally appeared to occur at the 95th and 99th percentiles, attributing to the effectiveness of both local and nationwide O3 precursor emission controls. The increasing trend in the 5th percentile indicates possible increased baseline ozone. Seasonal variability of O3 concentrations was present with 50th percentile O3 values in spring (45 ppbv) and summer (46 ppbv) being significantly higher than fall (36 ppbv) and winter (35 ppbv), in part due to the seasonal patterns of photolysis conditions and temperature. Although multiple studies have observed increasing trends in springtime O3 in the western U.S., no such spring trends were observed this analysis. The lack of significant trends may be due to the particular location and topography of the monitoring site, which is east of the Continental Divide and in the foothills of the Pikes Peak region, as well as the influence from the nearby urban emissions. We also performed cluster analysis of 10-day HYSPLIT back-trajectories generated for spring (April-May) and summer (June-August) and looked at O3 trends within each cluster. For spring, most of the clusters did not indicate significant linear trends; the only significant positive trend was associated with low-altitude transport over the Pacific (Cluster 2). For summer, a significant positive trend was found in the 95th percentile of Cluster 6, representing the low-altitude transport from the southeast. The wintertime 5th and 50th percentiles indicated significant increases, with slopes of 1.13 ppbv yr-1 (17.2% ppbv yr-1) and 0.3 ppbv yr-1 (0.93% ppbv yr-1). Rapid development of oil and natural gas industry around the area may contribute to these positive trends, and this is an area for future research.