Registered AR cover franked with single 1916 20c blue & lake with 'G.P.DE M' Silver Currency overprint in black and 'GOBIERNO $ CONSTITUTIONALISTA' overprint in also black (SG 334) tied by CAMPECHE, CAM cds dated 6 JAN 1917 with boxed 'CAMPECHE, CAM' registration marking in violet and circular 'AR' marking in black alongside. Addressed to USA with two blue 'Sunburst' registry seals on reverse tied by oval CERTIFICADOS CAMPECHE markings with various other transit and arrival marks. A fine franking.