The city honors Dr. Martin Luther King Jr. in a number of ways this long weekend, with the most broad-based activities – a march aligned with #BlackLivesMatter protests and the fifth Annual Cambridge MLK Day of Service – reserved for Monday, the actual King holiday.

The mix of activities makes good sense: In addition to being among the 20th century’s most important activists for social justice, he is famously quoted as saying “Life’s most persistent and urgent question is: ‘What are you doing for others?’”

Today saw kids age 7 through 18 serving people in need at the Harvest Food Pantry in Central Square. The kids worked from 9 a.m. to noon at Cambridgeport Baptist Church, 459 Putnam Ave., sorting donations, organizing clothing and guiding clients through the space, helping them find what they need, Crossroads for Kids president Deb Samuels said.

Sunday brings a free African American Heritage Trail Walking Tour from 1 to 2:30 p.m. Sunday at Mount Auburn Cemetery, 580 Mt Auburn St., West Cambridge. Volunteer Docent Steve Pinkerton’s guided tour will reveal the resting places of notable black authors, journalists, jurists, lawyers, politicians, musicians, athletes, entrepreneurs, activists and reformers buried in Mount Auburn during the 19th and 20th centuries. (Register for the tour here.)

Monday’s Day of Service is expected to see at least 2,500 volunteers work between 2 and 5 p.m. on various projects to benefit the homeless, homebound elderly and children and families. Led by  Many Helping Hands 365 and representatives from other city agencies, volunteers will sort food donations for food pantries; make fleece blankets for children at family shelters and homeless adults found sleeping outdoors; make bookmarks for The Literacy Project at Cambridge Public Library and the Community Learning Center; make Valentine’s Day cards for elders served by Meals on Wheels, as well as Cambridge veterans and military personnel; and put together activity kits for the children of families visiting city emergency waiting areas and toiletries kits for people at domestic violence and homeless shelters. More than 70 service organizations benefit from the citywide event.

“Cambridge is an extraordinary and generous community,” said Lori Lander, chief organizer of Many Helping Hands 365 and the Cambridge MLK Day of Service. “Last year, we had over 2,500 volunteers, and we expect more this year.”

The first event in 2011 drew 500 volunteers; the 2012 day drew 800; and the 2013 day drew some 1,500.

A brief welcome gathering will take place on the steps of City Hall, 795 Massachusetts Ave., Central Square, at 2 p.m. before dispersing volunteers to worker either in City Hall or at the YWCA, 7 Temple St. Volunteers can register here.

Volunteers are asked to “not come empty-handed,” and bring items such as winter clothing,  nonperishable food donations and children’s books to donate.

Many organizations use MLK Day as the springboard for service throughout the year. “The needs in our community are particularly great right now. Raising the awareness of these needs will take a sustained effort, and we hope many who volunteer on MLK Day will make an ongoing commitment to serve throughout the year,” said Bob Hurlbut, director of the Cambridge Community Foundation.

Also Monday, an opportunity for those with a more activist bent: A local 4 Mile March, which has events planned for nearly 30 cities as of Saturday afternoon.

The Boston march is to meet at the Old State House, which is the site of the Boston Massacre, near the State Street T station on the blue line, at 1 p.m. and march to the African Meeting House, 8 Smith Court, Boston.

The mission of the march is twofold, organizers say:

to bring awareness to America’s epidemic of racial profiling and police brutality, and to honor all those who have been injured or died as a result of police violence.

“One of the most important steps we can take is to build mounting pressure upon our local and federal government to do what is right,” organizers said. “Elected officials must mandate laws that will hold police accountable for every illegal and inhumane act they commit against the human rights of all citizens. We are demanding justice, particularly for those most often attacked and whose stories are rarely told: minorities, women, poor and low-income families, and the mentally ill.”

There have been several marches and protests stemming from recent overlapping examples of often fatal and unprosecuted police actions against people of color, including a new tactic of blocking freeway traffic.

On Thursday, State Police found a “human chain” of protesters linked together with PVC pipes, metal chains, ropes and carabineers, stopping southbound traffic near Exit 30 of Interstate 93, near the Century Bank building in Medford. Traffic was slowed or stopped for hours as police tried to separate members of the group, Middlesex District Attorney Marian Ryan said.

There were multiple arrests, and officials ultimately arraigned 18 people in Somerville District Court, asking them to return for a court hearing Feb. 20. Among the crowd were Somerville residents Kathryn Selcraig and David Voutour,

“While we respect the right of individuals to protest, this action jeopardized public safety,” Ryan said. “No one involved in civil disobedience has the legal right to trespass on a roadway with the intention of blocking traffic, let alone a major highway such as 93 during the morning commute.”