SWAP observations (thick lines) from 22 to 38 au and extrapolated radial trends (thin lines) of the solar wind (SW) dynamic pressure (black) and SW thermal pressure (blue), as well as the pickup H⁺ (pickup ion) pressure (red). Magnetic pressure (green dashed) and another measure of solar wind particle pressure (blue dashed) are taken from Voyager (Burlaga et al. 1996), and averaged values and ranges at 33 au come from Bagenal et al. (2015). Additional measurements of the pickup ion pressure from the Ulysses SWICS instrument out to 5 au and inferred values from pressure balance structures (PBSs; Burlaga et al. 1996) are plotted in red. Finally, values from a simple conservation model (see text) are indicated with triangles in matching colors at 30 au and the termination shock at 90 au, and values from the turbulence transport model (Adhikari et al. 2017) are indicated with stars.