  We investigate transport in locally-gated graphene devices, where carriers
are injected and collected along, rather than across, the gate edge. Tuning
densities into the p-n regime significantly reduces resistance along the p-n
interface, while resistance across the interface increases. This provides an
experimental signature of snake states, which zig-zag along the p-n interface
and remain stable as applied perpendicular magnetic field approaches zero.
Snake states appear as a peak in transverse resistance measured along the p-n
interface. The generic role of snake states disordered graphene is also
discussed.
