Question: the term reconstruction in united states history refers to the period after what event
[{'answer': 'American Civil War', 'provenance': [{'wikipedia_id': '55040', 'title': 'Reconstruction era', 'start_paragraph_id': 2, 'start_character': 127, 'end_paragraph_id': 2, 'end_character': 145, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]