This paper presents major results and comparisons of radio spectrum utilization measurements that have been carried out in two different locations in Izmir, Turkey. Analyzed radio spectrum extends from 30 MHz to 3 GHz. Utilization performance and behaviors of major primary wireless communication systems within different regions and different environments are investigated. The main outcome of the study is the low utilization profiles over the frequency bands of interest. Our analyses also pick out correlations between spectrum utilization within different regions and summarize common observations and physical aspects that should be considered in the future radio spectrum management to assure efficient spectrum utilization.