Metrolinx is Ontario's regional transportation agency responsible for integrated transportation planning and delivery in the Greater Toronto and Hamilton Area (GTHA). Metrolinx operates GO Transit (regional trains and buses), UP Express (airport rail link), and manages major transit expansion projects including new subway lines, light rail, and bus rapid transit. The agency coordinates regional transportation planning across multiple municipal jurisdictions, addressing the challenge of providing seamless transit across municipal boundaries. Metrolinx projects significantly affect municipal land use planning, as transit investments shape development patterns along corridors. The agency's relationship with local municipalities involves coordination on infrastructure integration and station area planning.