Twenty years ago, the average American police officer was a white man from a military background, without any college education.
The handful of female officers were not even allowed to ride in patrol cars after dark in some cities.
Today the police are more representative of the nation's racial makeup than many institutions, including Congress.
They are better educated than the typical worker. Women do almost every job that men do. And, contrary to public perception, they are less likely to kill or be killed on the job than at any time in the last two decades.
Last year, 65 officers were killed in the line of duty -- the lowest number since 1968 and about half the peak rate of 120 officers a year in the early 1970s.
And there are variations from place to place: Some cities have indeed become more violent. But in interviews around the nation, officers and experts said nightly television images of military-style drug busts and constant talk about a "war" on crime have created an impression that does not reflect modern reality among most of the nation's 500,000 police officers.
The war image has also been used in the videotaped beating of Rodney G. King, the black motorist who was clubbed and kicked by white police officers in Los Angeles last month. Whether or not the streets have become safer, what has changed considerably is the typical police officer.
According to studies by two police research agencies, the proportion of officers with college degrees has more than quintupled in two decades: to 23 percent, from less than 4 percent in 1970. And they are paid more money than the average American worker -- with a median annual salary of $29,066 last year compared with $21,580 for wage earners as a whole, the Labor Department says. Police officers widened that gap over the last decade.
"Police work used to be like a laborer's job," said Cmdr. Hugh Holton of the Chicago Police Department. "The only real requirement was you had to be tough. Now, that's not what we're looking for. You don't spend that much of your time actually fighting crime, I'd say only 4 percent of the job."
Like other officers interviewed, Commander Holton said a typical day was spent settling family disputes and doing other kinds of social work, answering calls that may go nowhere, untangling traffic and filling out paperwork.
Reflecting a sentiment voiced by officers around the country, Commander Holton said: "The job has become more complicated. People are demanding more. They want all kinds of services from us. It's come a long way from the us-versus-them days."
With the spread of crack and the violence that has accompanied its sale and distribution, the police are threatened as never before, the argument goes in cities that experience a particularly high level of violence.
"There is a very thin line between the complete chaos of some of our cities and civilization, and that thin line is our police department," said the Rev. Robert Rankin, who is the parish priest for Sgt. Stacey C. Koon, one of four Los Angeles police officers charged in the beating of Mr. King.
There are just as many police officers now per crime as there were 10 years ago. And for all the talk about proliferation of semiautomatic assault weapons, most police officers are still killed by ordinary handguns.
Last year 48 of the 65 police shooting deaths were from small pistols. More officers were killed by knives and fists than by shotguns.
"To cast the modern American police force in a military way -- as in the war on drugs -- is wrong," said Darrel Stephens, director of the Police Executive Research Forum, a non-profit group that studies police issues.