Values of the ratio of the longitudinal diffusion coefficient to mobilityDL/&mgr; for electrons in He, Ar, Kr, and Xe are derived from current waveforms obtained during earlier measurements of electron mobility. The electric field to gas density ratiosE/Ncover the wide range of 10−3to 20 Td, thereby bridging previous experiments at lowE/Nto recent experiments at highE/N. Here 1 Td=1×10−21V m2. The correspondingDL/&mgr; values range from 0.0066 eV for thermal electrons at 77 K to 10 eV. In addition to the well‐known peak inDL/&mgr; for Ar atE/Nbetween 0.01 and 0.1 Td caused by the Ramsauer minimum in the momentum transfer cross section, we find previously unreported low‐energy peaks inDL/&mgr; vsE/Nin Kr and Xe and previously unreported pronounced leveling‐off inDL/&mgr; atE/N≳8 Td in Ar, Kr, and Xe. Calculations of transport coefficients using numerical solutions of the Boltzmann equation and cross section sets in the literature give good agreement with experiment fromE/Nproducing thermal electrons up to average energies ≊10 eV andE/Nup to 100 Td, the upper limit of our calculations. The leveling off ofDL/&mgr; at highE/Nis caused by inelastic collisions.