Question: when did polygamy become illegal in the us
[{'answer': 'the mid-19th century', 'provenance': [{'wikipedia_id': '14757847', 'title': 'Polygamy in North America', 'start_paragraph_id': 13, 'start_character': 174, 'end_paragraph_id': 13, 'end_character': 194, 'bleu_score': 1.0, 'section': 'Section::::History of polygamy.\n'}]}, {'provenance': [{'wikipedia_id': '14757847', 'title': 'Polygamy in North America', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 307, 'bleu_score': 0.9603762111511761, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16769519410325205542}, 'section': 'Section::::History of polygamy.\n'}]}]