Around noon this Monday, runners will take to the streets for the 107th annual Boston Marathon. More than 20,000 runners from all 50 states and 58 countries have been training for months to run the 26 miles, 385 yards. But they aren’t the only ones busy preparing for the big day.

Half a million people are planning to miss work or school. Restaurants where customers are normally seated quickly on a Monday evening are booked solid for the whole day. And gallons of Gatorade and water wait to be set out on tables throughout the Boston area.

From international marathoners to local business owners and bus drivers, countless people will be keeping the city “running” safely and smoothly Monday. It’s a big job for any event in the city, but particularly important for one with the worldwide recognition of the Boston Marathon weekend.

In response to terrorism fears, police are removing newspaper boxes and the large metal trash bins around the crowded Kenmore and Copley Squares, and some have been trained to use special detectors that pick up traces of chemical or radioactive material, according to Boston Police spokeswoman Mariellen Burns. Officers will be deployed in front of crowds along the race route, concentrating on Kenmore Square because of the race and an 11 a.m. Boston Red Sox game at Fenway Park, but police will also be stationed behind the crowds for the first time as an added precaution, Burns said.

Burns also said people coming into the city should plan to take public transportation, as parking in Boston — already hectic on a weekday — will only get worse.

“No one should plan to drive — that’s been the case since there have been cars,” Burns said.

Luckily for them, the Massachusetts Bay Transportation Authority is also prepared.

“Service will be increased in anticipation of crowds,” said MBTA spokeswoman Lydia Rivera.

The 15 bus routes the marathon passes will be re-routed to avoid the race path, and will run on a Saturday schedule, Rivera said. The Blue, Orange, Red and Green Lines will all have enhanced service, Rivera said, though the Green Line’s Copley Station will be closed all day. Green Line riders will have access to the Copley Square area, where the marathon ends, through the Hynes Convention Center and Arlington stations.

Perhaps the world’s most famous marathon, this year’s race will attract 500,000 spectators, 7,000 volunteers and more than 1,100 members of the media, more than any one-day sporting event except the Super Bowl. The marathon will be televised locally, nationally and in 200 other countries.

And with the worldwide attention on Boston for the weekend, local companies have been preparing for one of their biggest weekends of the year as well.

Last year’s marathon brought an economic boost of $71 million, according to the Greater Boston Convention and Visitors Bureau. And with a 4,000-runner increase marathon-qualifiers, and their friends and family, local business officials have raised their economic expectations.

“It’ll probably have an even greater impact this year,” said Julia Beeson, spokeswoman for the Boston Athletic Association, the organization that plans and sponsors the marathon. Some predict as much as $74 million will flow through city businesses, creating a very lucrative — but very busy — day for local businesses.

Rich Valente, executive chef at the Legal Sea Foods on Boylston Street near the marathon’s finish line, said he sees the race’s economic effects every year.

“The restaurant gets very, very busy,” he said.

Not surprisingly, Legal Sea Foods is not accepting reservations for Monday, and as long as the weather is pleasant, will keep moving customers in and out all day.

“A lot of people just grab a quick bite, and then they’re back out on the street,” he said.

And all those hungry customers will no doubt need a place to stay.

“Folks have been calling from all around,” said Tom Keeves, director of Event Planning at the Boston Marriott Copley Place, which overlooks the home stretch of the race. Keeves said the Marriott is just about sold out, a yearly marathon tradition at the hotel which is assisted by a relationship with a local travel company that blocks off hotel rooms up to four years in advance.

“They get in there as soon as they can,” said Keeves, who already has committed rooms for the 2005 race.

The Beacon Inn, along the race route at 1075 Beacon St. in Brookline, has been booked since January. Manager Heather Diamond said one couple running, whose extended family will be in Boston for the race, reserved all 11 rooms. Diamond has a marathon-themed party planned for the group, though they might not need extra activities with all of the city’s other planned festivities.

And naturally, Diamond added, the two race competitors were given the bedroom on the ground floor to rest their legs after the race.

They probably won’t be the only ones in Boston ready to sit down Monday night.