BETWEEN getting out of his car and starting work in the morning, Bashir Akinyele, a beret-wearing history teacher in Newark, New Jersey, passes the sites of two murders. His school, Weequahic High, once taught Philip Roth, a giant among America’s novelists. Its entrance is now blocked by a metal detector; armed cops share the corridors with teenage girls. In the streets nearby almost every intersection has been the site of a shooting. “I’ve been a teacher for 20 years,” says Mr Akinyele. “And in that time, I’ve lost 38 students.”

Weequahic is only 30 minutes’ drive from Manhattan, but a world apart. In 1991 Newark and New York City had roughly the same murder rate: 32 and 29 per 100,000 respectively. But by last year New York’s rate had fallen to four and Newark’s had jumped to 40, according to the latest data published on November 14th by the FBI. On a night out in Brooklyn, the main threat is getting caught in a boring conversation with a hipster. In Newark, when darkness fell, your correspondent was ushered back downtown by police.

Over the past 20 years, crime has fallen spectacularly in America and across the rich world. The FBI data suggest it is still falling: violent crime decreased by 4.4% between 2012 and 2013, and murder is now less common than at any time since the end of the 1950s. Criminologists have countless plausible theories to explain this, ranging from less lead-poisoning to the rise of car immobilisers. Yet the difference between cities such as Newark, which remain dangerous, and those like New York, which are safe, suggests a somewhat subtler explanation.

In Washington, DC the murder rate has dropped from a terrifying 81 per 100,000 in 1991 to a fifth of that now. In Los Angeles gang warfare has largely given way to organic coffee bars, and burglaries and robberies have become rare. Yet cities like Philadelphia and Chicago have experienced more modest improvements. And in places like Baltimore, Newark and Detroit some crime rates have barely fallen.

One possible explanation is the varying quality of local government. In New York and Los Angeles, reformers such as Rudy Giuliani, who was New York’s mayor in the 1990s, and Bill Bratton—chief of police in both cities at different times—forced cops out of their cars, adopted data-driven policing and tried to make public spaces feel safe. They reckoned that residents had to trust the police for crime to fall—which meant purging corruption—and that criminals had to be deprived of convenient places to hang out.(Economist)

翻译：

Bashir Akinyele， 一个戴着贝雷帽的新西泽州纽瓦克市的历史老师，早上在离开他的车去工作的过程中，经过两个谋杀案的现场。美国小说巨匠Philip Roth毕业于他教书的学校——Weequahic 高中。这个高中的入口现在被金属探测器堵住了，武装好的警察和青少年女孩都在走廊上。在附近的街道上几乎每一个十字路口都发生过枪击案。“我做老师已经20年了”， Akinyele先生说，“在这期间，我失去了38名学生。”

Weequahic 距离曼哈顿只有三十分钟的车程，但是却是两个世界。在1991年纽瓦克市和纽约有差不多的谋杀率，分别是3.2%和2.9%。但是根据美国联邦调查局11月14号颁布的最新数据，去年纽约的谋杀率已经降到了0.4%但是纽瓦克市的谋杀率却上升到了4%。在布鲁克林晚上外出的最大威胁是跟一个潮人进行无聊的对话。在纽瓦克市，当夜幕降临后你的联络人会被警察带回市区。

在过去的20年，美国和富有地区的犯罪率明显降低。美国联邦调查局的数据显示犯罪率还在降低：暴力犯罪率在2012到2013年间下降了4.4%，现在的谋杀率19世纪50年代末以来历史最低。犯罪学家有无数的貌似可行的理论来解释这个现象，从更少的铅中毒到更多的汽车防盗器。现在纽瓦克市这类仍然很危险的城市和纽约这种安全的城市之间的差别在一定程度上表明了微妙的解释。

华盛顿1991年的犯罪率是惊人的8.1%，现在下降到当初的五分之一。在洛杉矶，有组织的咖啡吧很大程度上取代了帮派群架，偷盗行为也变得更稀少了。现在费城和芝加哥这类城市已经经历了一个较为温和的改善。但是巴尔的摩、纽瓦克市和底特律这样的城市犯罪率几乎没有下降。

一个可行的解释是地方政府的质量不同。在纽约和洛杉矶，Rudy Giuliani(1990年担任纽约的市长)和Bill Bratton(在不同的时间担任过两个的城市的警长)这类的改革者命令警察到他们警车以外的地方，采取数据驱动政策并且努力使公共区域感到安全。他们希望居民相信警察能够使犯罪率降低，这意味着清除腐败，以及犯罪者会从方便大家闲逛的地方被清除。