HARARE, Zimbabwe — Zimbabwe’s Robert Mugabe resigned as president Tuesday after 37 years in power, as parliament began impeachment proceedings against him. “My decision to resign is voluntary on my part and arises from my concern for the welfare of the people of Zimbabwe and my desire for a smooth, non-violent transfer of power,” said Mugabe in his letter which was read out in parliament, sparking cheers and dancing. Cars began honking horns and people cheered in the streets, as the news spread like wildfire across the capital, Harare. Mugabe, who had been the world’s oldest head of state at 93, said that proper procedures should be followed to install new leadership. Mugabe’s resignation brought an end to the impeachment proceedings brought by the ruling ZANU-PF party after its Central Committee voted to oust the president as party leader and select recently fired Vice President Emmerson Mnangagwa as his replacement, a move that eventually could lead to Mnangagwa becoming head of state.