Turbine nozzles and cooling systems for cooling slip joints therein are provided. The turbine nozzle has an endwall, a vane coupled to the endwall, a slip joint, and a plurality of airfoil quenching holes that cooperate with a plurality of endwall cooling holes. The vane comprises a leading edge and a trailing edge interconnected by a pressure sidewall and a suction sidewall and an end portion. The slip joint is between the end portion and the endwall. The airfoil quenching holes are defined through the pressure sidewall in the end portion. The endwall cooling holes are defined through the endwall along the pressure sidewall and in proximity to the leading edge. The airfoil quenching holes and endwall cooling holes are disposed adjacent the slip joint.