One of the key issues in this US election is immigration. Donald Trump often refers to ‘border chaos’, warning of out-of-control ‘migrant crime’ and accusing Kamala Harris of allowing "20 million criminals” into the country. Yet statistics show the number of irregular border crossings from Mexico have dropped significantly over the last year. SBS News has travelled to the very south of Arizona to see if Mr Trump’s rhetoric in any way matches the reality.