Question: when was thanksgiving declared a holiday in the united states
[{'answer': '1863', 'provenance': [{'wikipedia_id': '8304348', 'title': 'Thanksgiving (United States)', 'start_paragraph_id': 1, 'start_character': 453, 'end_paragraph_id': 1, 'end_character': 457, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '8304348', 'title': 'Thanksgiving (United States)', 'start_paragraph_id': 1, 'start_character': 102, 'end_paragraph_id': 1, 'end_character': 910, 'bleu_score': 0.56162033421375, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12672626137574384662}, 'section': 'Section::::Abstract.'}]}]