Headed 'Republica de Colombia Intendencia Nacional del Choco Direccion de Educacion Publica' cover franked with single 1937 5c brown 'OFICIAL' overprint issue (SG O498) tied by QUIBDO cds. Sent airmail to BOGOTA with large 'Correo Aereo' markings on front and official cachet on reverse all in blue. Arrival cds also on reverse.