With zero fanfare, Fairfax County quietly released crime statistics showing that in 2014, the Washington region’s largest jurisdiction recorded its lowest crime rate in its statistical history, dating to 1970.

As in previous years, the number of homicides in Fairfax was low: 10 in a population of 1.1 million, and that was an increase from the eight slayings in 2013. But in the six other major categories, crime plummeted in the county, including fewer than 1,000 burglaries for the first time and a record low 733 stolen vehicles in 2014.

Fairfax’s drop was mirrored in Arlington County, which posted its lowest crime rate since 1961; Alexandria, which maintained a crime rate not seen since the 1960s; and Prince George’s County, which recorded a 9 percent drop in serious crime; and Loudoun County, with a 5 percent decrease.

Montgomery County saw a 10.6 percent rise in serious crime in 2014, and statistics were not yet available for the District and Prince William County.

Fairfax’s total number of serious “Part I” crimes — defined by the FBI as homicide, rape, robbery, aggravated assault, burglary, larceny and auto theft — was 15,703 last year, a 4.6 percent decrease from 2013. Between 1974 and 1997, that total was typically above 25,000 serious crimes, with about 2,000 burglaries and 2,000 vehicles stolen each year.

But in 1998, that number began a steady decline, even as Fairfax’s population shot upward, from about 880,000 in 1995 to an estimated 1.11 million in 2014. Fairfax police also began a more detailed “incident-based” system of crime reporting in 2011, designed to capture additional data, but the county’s numbers have still declined.

Chief Edwin C. Roessler Jr. said that the police were not manipulating the data but that they also did not see the new numbers as “something to jump up and down and celebrate. For every crime, there’s a victim.”

Roessler did note that police efforts to handle domestic violence cases more carefully might be having an impact: Only one of the 10 slayings in Fairfax was domestic-related last year. Fairfax police have issued a cellphone to every patrol officer and are doing “lethality assessment” training so that officers can better analyze the potential for future trouble on domestic calls and offer guidance on a full range of assistance to those who need it.

Where once there were 6,380 burglaries in Fairfax in 1980, there were only 912 last year, statistics show, an all-time low for the county. Roessler attributed that to “community engagement” by officers, reminding citizens to “reduce opportunity for criminals by locking doors, windows and garages.” He said a diversity council he formed had helped police involvement in immigrant communities that formerly distrusted the police.

In Arlington, more serious crimes dropped 8.9 percent in 2014, with burglaries down 14.2 percent and aggravated assaults down 19.4 percent. Former police chief M. Douglas Scott, who stepped down last month, also credited “the partnership among the community and police department. We will continue to make these partnerships even stronger, as it has made our community safer.”