By Brendan O'Brien and Ian Simpson

MILWAUKEE/WASHINGTON (Reuters) - A year after a gunman massacred 26 first-graders and adults in a Connecticut elementary school, educational officials across the United States continue to face the longstanding question of how to best protect their students.

Principals and administrators across the country in many cases are choosing between technologies such as electronically controlled doors and the addition of security staff.

For one district, the Richmond School District outside Milwaukee, that has meant spending $24,000 to protect its one building with buzzer-entry doors and better lighting but choosing to skip bullet-proof glass.

"Our goal was to delay or deter intruders until the police could respond. Bullet-proof glass didn't fit that criteria for us," Superintendent Jeff Weiss said in an interview.

The school opted for stronger door frames and made improvements to lighting in its parking lot. The school also placed metal security screens over windows and doors so if the glass is broken, an intruder is still kept out.

The district joined hundreds in the United States that in the last year have wrestled with how to prevent a shooting.

The solution has been a mix: more and better-trained guards, and billions of dollars of security technology.

Schools are aiming to stop gun scares and killings, such as the shooting deaths of three students at an Ohio high school in February 2012, the wounding of two students at a California high school in January 2013 and a potential mass shooting at a Georgia elementary school in August that was averted when a school bookkeeper talked the gunman into laying down his AK-47 assault rifle.

The number of school resource officers or law enforcement officers assigned to schools has risen to levels not seen since the aftermath of the 1999 Columbine High School "massacre" in Colorado, in which 13 people were shot to death, said Maurice Canady, executive director of the National Association of School Resource Officers.

MORE TRAINING

NASRO said it has trained slightly more than 1,800 officers in 2013, a figure that Canady said is twice that of last year. The training includes how to deal with a gunman, as well as day-to-day security issues like drugs and gangs.

"Let's face it, most officers are never going to face an active shooter," Canady said.

A survey of 600 school districts published this month by Campus Safety, an industry magazine, showed that 88 percent of schools from kindergarten through 12th grade made changes in security after Sandy Hook.

Pointing to a booming market for school security systems, the IHS Inc business consultancy forecast in July that U.S. schools would spend $4.9 billion on buzzer doors, security lights and other hardware by 2017, compared with the $2.7 billion they spent on similar equipment in 2012.

In Alaska, the 48,000-student Anchorage School District used a $6.4 million state grant to improve communications systems, as well as add surveillance cameras and gear to lock down schools in case of an emergency.

"They are not perfect measures and they will not deter or prevent every potential type of an attack that could be conceived of, but they will make the schools safer," said Michael Abbott, the district's chief operating officer.

Anchorage is one of many U.S. school districts benefiting from a flood of federal and state money for school security, much of it given out since Newtown.

The Department of Justice said in September it was spending almost $45 million for 356 new school officer positions. The single largest grant was $2.25 million for 10 officers in Bridgeport, Connecticut, about 20 miles southeast of Newtown.

COP ON CAMPUS

"It used to be if you had a cop on the campus, people would see it as something wrong with the school. Now, it's seen as an advantage," said Ronald Stephens, executive director of the National School Safety Center, a California non-profit that provides training and advice on school security.

Congress is weighing President Barack Obama's request for $150 million in the fiscal year that started on October 1 for school safety under the Community Oriented Police Services program.

Individual states have also stepped up spending. Connecticut in November paid out $16 million in school-safety grants, following $5 million two months before. Virginia has awarded $6 million for school security.

Wayne LaPierre, chief executive of the powerful National Rifle Association gun lobby, has advocated putting a police officer in each of the 99,000 U.S. public schools.

In 2007, the last year for which U.S. Justice Department figures are available, there were 18,000 to 19,000 school resource officers. The Congressional Research Service estimated in a June report that it would cost at least $2.6 billion to put a police officer in each school.

After Newtown, seven states passed laws letting employees and, in some cases, average citizens to carry firearms in K-12 schools, according to the Law Center to Prevent Gun Violence in San Francisco.

Alabama also authorized the formation of volunteer emergency security forces at public schools, it said.

Despite the shootings at Newtown and other cities, data shows that schools are relatively safe places.

On average, 23 children aged 5 to 18 were murdered each year while at school between the 1992-93 and 2010-11 school years, according to U.S. Education Department data. That represented less than 2 percent of total homicides for that age group, the department said.

That still leaves room for improvement, security advocates said.

"When you're talking about young lives, one is too many," said Larry Johnson, president-elect of the National Association of School Safety and Law Enforcement Officials, which oversee school security programs.

(Editing by Scott Malone and nSteve Orlofsky)