The U.S. could be facing more increases in violent crime during a period of serious political divisions, says Ohio State University historian Randolph Roth, who studies crime trends.
"We're entering a period of intense political instability. And I'm worried that the homicide rate is going to go way up," Roth told a webinar hosted by the Harry Frank Guggenheim Foundation.
Roth wrote the book "American Homicide" and is co-founder of the Historical Violence Database.
Four factors correlate with high murder rates, Roth said: Political stability, legitimate government, racial resentment, and affinity among citizens.
Roth defined political stability is the belief that the government is stable and that its legal institutions are unbiased and have the ability to "redress wrongs and protect lives and property."
The most significant measure of political instability is the number of protests and riots that lead to fatalities due to violence by law enforcement authorities, against authorities, or among civilians.
Compared to the colonial period, the measurement could be applied to the "banishment of people for political or religious dissent, executions for sedition, treason, heresy, and witchcraft, and deadly riots during political or community disputes," Roth said.
Homicide rates have increased during sharp divisions over war, taxes, and Jim Crow laws.
Roth correlated high-profile police shootings of Black men starting with Michael Brown in Ferguson, Mo., in 2014, and the white supremacy movement with the current period of political instability.
Legitimate government is measured by the popular feeling of trust in the government and those who run it.
Racial resentment and affinity among citizens refer to the fellowship of people that transcends race and religion.
"These feelings and beliefs are closely interrelated. They have a synergistic effect with the homicide rate when the homicide rate rises," Roth said.
Roth said the loss of government legitimacy or fellowship can cause homicide rates to rise. That may continue to reduce the public's belief that the government can protect lives, leading to a further increase in homicide.
"An increase in homicide can also change the character of a society's social hierarchy and make violence a means of winning respect," Roth said.
However, when citizens believe that the government is stable and feel a strong bond with others, violence is not necessary for respect.
"Nothing suppresses homicide within a social group, more powerfully than a sense of connectedness that extends beyond the bounds of family and neighborhood, and forms a strong bond among people who share race, ethnicity, religion, or nationality," Roth said.
He said these beliefs in most societies are either entirely absent or not widely shared, which is why homicide rates fall between extremes "Homicide rates can fall to two per 100,000 adults per year or even lower," he said.
The U.S. homicide rate in 2020 was 7.8 per 100,000, the highest since 1995 and a record increase of about 30 percent over to 2019.