At 9:34 on a recent Saturday night, Fort Washington resident Donald Harris called Prince George's County police to report a five-car pileup on Allentown Road. A dispatcher entered the call into a countywide computer database as Harris waited at the scene.

At 10:55, Harris was still waiting and called again, asking to speak to a supervisor this time. None was available. And the police cruiser sent to the accident scene had been diverted to another call. Harris left a cell phone number, and a note was typed into the database.

Harris's calls were among about 60 requests for assistance put on hold at that hour on June 19, according to a printout from the county's 911 call center. Other callers waited for officers to respond to disorderly conduct, stolen cars and the sounds of gunshots and house alarms ringing through the night.

It wasn't a particularly busy weekend: Harris's request for service was the county's 1,452nd emergency call of the day for a department that averages 2,000 calls daily. The backlog repeats itself on any given day because of an increasing shortage in manpower -- created not only by staff vacancies but also by an organizational structure that police union leaders say channels many officers away from the street.

"You can see that it isn't a one-time thing, that this is happening every night," said Cpl. Donnie Bell, vice president of the Fraternal Order of Police Lodge 89. "Even if it's a top priority call, if there's no one available, then there's no one available to send."

The county has authorized funding for a police force of 1,420 sworn officers, but through April there were just 1,250 officers. Of those, 488 were assigned to respond to calls -- about 39 percent of the force -- according to a police unionaudit. That amounts to less than one officer for every 1,000 of the county's 833,000 residents.

"We have officers calling in all the time talking about staffing levels," Bell said. "Officers are running calls everywhere in the county because there aren't enough of them on patrol."

The Justice Department has no standard for staffing, but experts say that in general, police departments allocate half the force to answering calls.

Police in Montgomery and Anne Arundel counties said they assign roughly half of their officers to the streets. Across the Potomac in Fairfax County, 85 percent of the force responds to calls, according to a 2000 Justice Department report.

Prince George's County Police Chief Melvin C. High said that department leaders recognize there are "challenges associated with the deployment and the allocation of resources" in the county and added that they are working hard to strike "a balance between the number of people we have on patrol to answer calls for service and the number of detectives we have ready to respond to crime scenes. One of our priorities is to be timely in our responses," he said.

Many calls don't require an immediate response, High said, and those can be answered by the department's telephone reporting unit -- officers who take reports and immediately enter them into the computer system. The unit is especially helpful in handling stolen car reports, more than 16,000 of which were received last year in the county, the chief said.

"We want our police to be as efficient as they can be, and this is something that is convenient for the community and far more efficient," High said. "Otherwise they have to wait and wait."

Priority calls include those with a possible crime in progress, such as a house alarm, or an accident with injuries, officials said. The accident Harris called about led to at least two minor neck injuries, but an ambulance arrived within minutes and was able to care for the patients, said Bell, the union officer.

However, for major incidents such as slayings and shootings, officers are rerouted from wherever they are or sent from across the county, Bell said.

A larger police force could reduce the wait times, officials agree, and adding at least 150 officers to the department is a chief goal.

More officers on the street won't necessarily reduce crime, said John Eck, a criminologist at the University of Cincinnati. But increased staffing could reduce the stress that inevitably accumulates for officers who run from call to call, said Larry Hoover, director of the Police Research Center at Sam Houston State University in Huntsville, Tex.

Having too few officers, Hoover said, forces those on the street to develop an "urgent sense that they need to become available for the next 911 run."

But the Prince George's force, which was recently the subject of a top-to-bottom federal civil rights probe, is not as attractive to new recruits as neighboring jurisdictions that record less crime and offer better incentives, said Percy Alston, the union's president.

"We all understand -- the union, the department, the county -- that we need more manpower. The only thing we can do is be the best salespeople to assist in recruiting," Alston said. "We're losing the battle in this region to get good, qualified, educated people."

Nineteen recruits -- three women and 16 men -- graduated from the police academy June 24. They were assigned to field training officers in the six police districts, with whom they will ride for 90 days. But by the time they are released and on their own, at least that many officers will have retired, Alston said, adding that on average, seven officers retire every month. The next class of recruits will graduate in the fall.

But even without the added personnel, the department could free up more officers with organizational shifts, union leaders said.

"It's hard to justify some of the specialized units when you have people waiting as long as some of the residents do," Bell said. "Sure, some of the calls are huge priorities, but when you answer a call, you need to make the citizen feel like theirs is the most important call of the day."

That's certainly not how Harris felt the night he called about the pileup.

According to the printout, another officer was dispatched to the scene at 11:01 p.m., about 90 minutes after the first call was received, then was rerouted eight minutes later. Finally, at 11:25 p.m., an officer arrived, nearly two hours after Harris phoned in the emergency.

"It was frustrating," Harris said in a recent interview. "They called me later and I said, 'I'm at home now. I don't need you now.' "

He wasn't the only one left waiting.

At 4:58 p.m. June 20, for example, 64 calls were awaiting a police response, including one for a stolen auto that a 911 caller had phoned in 497 minutes earlier -- more than eight hours.

Later that same Sunday, at 11 p.m., 58 calls were holding, including one for gunshots that had been heard more than two hours earlier and another for a raucous party that had been deemed too loud by one resident at 8:46 p.m.

About a month earlier, on May 21 at 9:24 p.m., 45 calls were on hold, including a report for a missing person that had been pending for almost five hours. An accident had not been tended to after 170 minutes, loiterers had not been shooed away after 63 minutes, and suspicious activity in the Palmer Park district had not been checked after 87 minutes.

At a recent police academy commencement, only 19 graduates were about to enter the Prince George's force. Cadets line the back wall at the police academy graduation for Prince George's County. Only two or three classes complete training each year.