Question: how long is the us border with mexico
[{'answer': '1,989 mi'}, {'provenance': [{'wikipedia_id': '2817606', 'title': 'Mexico–United States border', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 382, 'bleu_score': 0.8931660737852121, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8971181831105282686}, 'section': 'Section::::Abstract.'}]}]