  We consider mixtures of oppositely driven particles, showing that their
non-equilibrium steady states form lanes parallel to the drive, which coexist
with transient jammed clusters where particles are temporarily immobilised. We
analyse the interplay between these two types of non-equilibrium pattern
formation, including their implications for macroscopic demixing perpendicular
to the drive. Finite-size scaling analysis indicates that there is no critical
driving force associated with demixing, which appears as a crossover in finite
systems. We attribute this effect to the disruption of long-ranged order by the
transient jammed clusters.
