Question: when was the first zoo opened in the us
[{'answer': 'July 1 , 1874', 'provenance': [{'wikipedia_id': '472951', 'title': 'Philadelphia Zoo', 'start_paragraph_id': 5, 'start_character': 76, 'end_paragraph_id': 5, 'end_character': 91, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '472951', 'title': 'Philadelphia Zoo', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 533, 'bleu_score': 0.950027409461844, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9113585292924291954}, 'section': 'Section::::Abstract.'}]}]