BAGRAM, Afghanistan (AP) — Bagram Airfield has been the heart of American military power in Afghanistan for nearly 20 years. It was a sprawling mini-city behind fences and blast walls just an hour’s drive north of Kabul. In just a matter of days, the last U.S. soldiers will depart the base. They are leaving behind a mixed legacy. The base had been a major supplier of employment for dozens of surrounding Afghan villages. But the notorious prison at the base also struck fear among many Afghans. Once the Americans are gone, the Afghan military will take over Bagram as part of its continuing fight against the Taliban.