In spite of disturbing headlines about war and terrorism, most of the world actually got safer in 2017. A review of the latest data reveals a noticeable drop in murder when compared to 2016. The reductions are especially pronounced in those parts of the globe that typically register the highest levels of violent crime. Take the case of the world's most murder-prone region: Central America's northern triangle witnessed a 23% decline in killings when compared with 2016.

While declining lethal violence is cause for cautious optimism, it is not evenly distributed. On the one hand, most advanced economies experienced continued declines in murder, though from baselines that were already at historic lows. On the other, there are still a handful of countries and cities, especially in Brazil and Mexico, struggling to shake off high rates of homicide. They are also fears that rising numbers of "disappeared" may explain the decline in murder in some countries. Major data gaps in poorer settings makes it hard to confidently track changes over time.

As in previous years, Latin American and Caribbean countries still lead the world in terms of crime and violence. The five countries reporting the highest homicide rates internationally in 2017 included El Salvador, Honduras, Jamaica, St Kitts and Venezuela. In 2016, 43 of the 50 most violent cities were situated in the region; when the data becomes available, it is likely that the rankings will tell a similar story in 2017. But even some of these countries and cities still managed to put a sizeable dent in their murder problem.

Take the case of El Salvador, ranked as one the planet's most murderous countries over the past four years. El Salvador dropped its homicide rates by 26% between 2016 and 2017. The current national homicide rate of 60 per 100,000 still places it at the top of the global ranking, but it is almost half of 2015 rate of 103 per 100,000. Meanwhile, San Salvador, the country’s capital, reported a reduction from 136 to as low as 70 per 100,000.

Neighbouring Honduras also recorded sharp reductions in homicidal violence in 2017. The murder rate dropped by 28% to 46 per 100,000 last year. Declared the world's most murderous city from 2012 to 2014, San Pedro Sula experienced a decline of 50% last year. Taking the slightly longer view, the homicide rate dropped from a high of 193 per 100,000 in 2013 to just 51.4 per 100,000 in 2017. Similar declines occurred in Belize, Guatemala and Puerto Rico. In all these countries and cities, years of investment in criminal justice reform are paying off.

The turnaround in many Central American countries is in sharp contrast to the tragic recent history of Mexico. The ratcheting-up of clashes between organized crime and state security forces, together with increasing inter-personal violence, contributed to a dramatic 20% spike in murder there in 2017 compared with 2016. Mexico's homicide rate of over 23 per 100,000 is double that of 2005, the year before former Mexican President Felipe Calderón launched a disastrous war on drugs. For the first time this year, Mexico will be listed in the top 20 countries experiencing the highest homicide prevalence rates.

There are equally worrying signs of deteriorating security in parts of the Caribbean. Specifically, homicidal violence has continued to increase in Jamaica, in part because of gang rivalries, but also due to growing levels of petty crime. The island nation has a murder rate of 56 per 100,000, the second highest in the world. Likewise, Trinidad and Tobago, registering a homicide rate of 36 per 100,000, has seen a fourfold increase since 2000, when its rate was hovering closer to 9.5 per 100,000.

The view from South America is mixed. On the positive side of the ledger, Colombia continued its extraordinary downward trend in homicides in 2017, a pattern that started in 2002. The country experienced a 5% drop in murder in relation to 2016. Continuous improvements in public security are taking place against growing popular dissatisfaction over the peace accord with the guerrilla group FARC. Indeed, despite continued declines in homicide, there are still rural parts of the country registering high levels of victimization.

As for Venezuela, it is hard to know what is going on since the government has not released official figures for over a decade. Unofficial reports suggest homicides actually reduced in 2017 by 12%. Even so, with a purported murder rate of 53.6 per 100,000 (the government says it is closer to 47 per 100,000), Venezuela would still rank among the top three most violent countries in the world. There are signs, in addition, that state killings increased last year. If one added state killings to the homicide tally, the rate would increase to 89 per 100,000, albeit still lower than the combined rate of 2016 (91 per 100,000).

Brazil has yet to release its 2017 data, though early indications are that homicidal violence has increased. Brazil's has the highest absolute number of murders in the world – accounting for 1 in every 10 murders globally. The Brazilian Public Security Forum, a network of research institutions, registered 57,395 homicides in 2016. But early data released by state secretaries suggests the numbers will top 60,000 murders in 2017. Brazil's homicide rate of roughly 30 per 100,000 is sufficiently high to ensure that it is among the top 15 most murderous countries.

Finally, the United States will likely also register a modest reduction in homicidal violence in 2017. While comprehensive national data is still not publicly available, the national decline could be due to a modest drop in rates in the country's 30 largest cities. Some of the country's most violent cities experienced significant declines in murder over the past year including Detroit (-13%), New Orleans (-10%), Newark (-27%) and Chicago (-15%) – a contrast to the slight increase observed in 2016. AT the same time, the country's most violent city, Baltimore, saw its murder rate increase from 51 to 56 per 100,000.

While varying from place to place, homicidal violence is declining in most countries and cities around the world. Many other forms of violence also appear to be dropping as well. While there are still pockets of extreme insecurity, such as war-torn parts of Afghanistan, the Democratic Republic of the Congo, South Sudan, Syria and Yemen, these tendencies align with psychologist Steven Pinker's claims the world is becoming progressively safer, in spite of unsettling media headlines. Notwithstanding this hopeful news, it is worth recalling that there homicides are only one measure of human suffering.

More positively, recent experiences in some Latin American countries show that improvements in security are possible. A focused strategy combining problem-oriented policing and social prevention measures in so-called "hot spots" can reduce homicides further still. Take the case of Bogotá, where just 1.2% of street addresses account for 99% of homicides. Or consider El Salvador, where young males (aged 30-34 years old) face homicide rates of 420 per 100,000, or 60 times the global average.

While the road ahead is challenging, the story from Latin America shows that violence is not inevitable. With the end of Colombia's five-decade civil war, Latin America is officially "conflict-free". While it is true that deaths resulting from terrorism and war have risen over the past few years (after a half-century decline), homicides are moving in the opposite direction. It is also the case that homicidal violence is especially clustered in a small number of regions – namely Latin America, the Caribbean and parts of sub-Saharan Africa and South-East Asia – but declining just about everywhere else.