  The observation of non-saturating classical linear magnetoresistivity has
been an enigmatic phenomenon in solid state physics. We present a study of a
two-dimensional ohmic conductor, including local Hall effect and a
self-consistent consideration of the environment. An equivalent-circuit scheme
delivers a simple and convincing argument why the magnetoresistivity is linear
in strong magnetic field, provided that current and biasing electric field are
misaligned by a nonlocal mechanism. A finite-element model of a two-dimensional
conductor is suited to display the situations that create such deviating
currents. Besides edge effects next to electrodes, charge carrier density
fluctuations are efficiently generating this effect. However, mobility
fluctuations that have frequently been related to linear magnetoresistivity are
barely relevant. Despite its rare observation, linear magnetoresitivity is
rather the rule than the exception in a regime of low charge carrier densities,
misaligned current pathways and strong magnetic field.
