Fine line

An aerial photograph of the US-Mexico border, taken from Playas de Tijuana in Baja California, shows where an existing wall divides the two countries, with Mexico on the right. Since the beginning of his presidency, Donald Trump has changed his mind about the design of new parts of the wall, including plans for it to be 50ft high and made entirely from concrete, or plans for a 30ft wall made up of “artistically designed steel slats”.