Summary of the N₂H⁺-based linewidth-size data explored in this paper. Blue symbols give characteristics of structures of varying spatial size explored here; see Sect. 3.4 for terminology and details. The blue crosses with white filling indicate data for the Sgr D region that probably resides outside the CMZ as studied here. The gray shaded region summarizes the linewidth-size measurements reported by Shetty et al. (2012). Dark green bullets indicate the properties of reference Milky Way clouds from the Kauffmann et al. (2013a) compilation that is based on emission lines of N₂H⁺ and NH₃ that trace dense gas. Light green diamonds give CO-based data for the lower density gas in Milky Way clouds reported in the same collection. The dotted line is defined by a crossing time of 3 × 10⁵ yr.