Where'd everybody go?

Driving miles, or hours, to work is a way of life for many people in communities south of Boston. But in all the attention paid to the long commute each morning, it's easy to forget what they leave behind -- daytime ''ghost towns."

A recent analysis released by the US Census Bureau found that four local communities -- the towns of Hull, Abington, and Holbrook, and the Ocean Bluff and Brant Rock neighborhoods in Marshfield -- are among the top 10 most-vacated places in the state, losing more than a quarter of their populations each day.

Overall, nine communities south of Boston lose more than 15 percent of their populations during the daytime.

The ebb and flow of commuters shapes everyday life in subtle ways, starting with having to wait in line at the local drive-up ATM at 6 a.m. as the commuting exodus begins.

Consider Hull. Each day more than 4,000 of its residents head out of town in a stream of cars along Nantasket Avenue, shrinking the population by more than a third. What is left behind is a commercial strip that can look nearly deserted at midday. Even as the town's year-round population has grown, few people work in town.

''We're remote; we're a destination point," rather than a community that people pass through on their way somewhere else, Lawrence Kellem, former president of the Hull Nantasket Beach Chamber of Commerce, said of the peninsula.

In Southeastern Massachusetts, the entire coastal South Shore is a ''commuting hot spot," according to an October 2004 study by the Massachusetts Institute for a New Commonwealth. The southeast corner of the state is also the region with the greatest share of ''long" commuters, with more than one in five workers spending 45 minutes or more in transit each day.

The Brant Rock and Ocean Bluff sections of Marshfield lead the list of communities that shrink during the day. The list was compiled by dividing the state into ''Census-designated places" that are towns or portions of towns.

Nearly half of Marshfield's oceanside neighborhoods disappears each morning.

On one recent weekday afternoon, the stillness of the Brant Rock Fish Market was broken only by the gurgling of the lobster tank. Outside, the parking lot was empty.

''We open at 9 a.m. We didn't have a customer until 11 a.m.," said owner Henry Dunbar as he opened the cash register to tally sales. ''There's not much to do around here. It's quiet."

Until about 7 p.m. Then, constant as the tide, the parking spaces begin to fill up, said Linda Melville, owner of Embellishments salon. She said she painted over the pink walls of her salon to better appeal to fishermen, who make up a large part of her customer base.

Abington loses nearly as many people as Hull during the day but it isn't as obvious, said Town Manager Phillip Warren Jr. Although there's always a boom in traffic during rush hour, with routes 139, 58, 18, and 123 weaving through the town and a commuter rail stop, the flow of people is pretty constant and the streets rarely feel deserted.

On the opposite side of the ebb-and-flow spectrum is Braintree, which swells by 10,250 people each day, making it the ninth-largest inflow of people among the places ranked by the Census analysis.

''The amazing thing is that doesn't even include people stuck trying to get through the [I-93, Route 3] split," said John Stobierski, communications manager of the South Shore Chamber of Commerce, noting that not just workers but commuters and shoppers visiting South Shore Plaza fill Braintree during the day.

''We've always had a large employment base. The town is maybe cursed and gifted; I'm not sure which," said Peter Lapolla, Braintree's planning and conservation director. ''My guess is, it's location, location, location. Easy on and easy off to the highway, you've got a fairly decent road system."

Four south-of-Boston communities grow by more than 15 percent during the daytime.

David Luberoff, executive director of Harvard University's Rappaport Institute for Greater Boston, said that statewide the suburbs have been growing in importance as both residential and workplace centers.

But the trend hasn't been as visible in communities south of Boston. Between 1990 and 2000, 75 percent of the job growth in Eastern Massachusetts occurred along the Interstate 495 belt, much of it west of Boston, according to Luberoff.

''What you're seeing on the South Shore," he said, ''is that some communities have [either] made a conscious decision that they don't want large commercial developments, or [there is] something about the market that means there hasn't been a huge demand out there."

Many local towns seem to fit in a middling place where the rush of people through town ebbs and flows.

In Scituate, which loses 7.6 percent of its population each day, the daytime population seems to depend on the temperature, as is the case in many of the coastal towns south of Boston. ''If the weather is good, you will see a lot of foot traffic here in the harbor -- people getting out, banks are busy. I see families out walking with their kids, going to feed the birds," said Dan Taylor, assistant vice president of South Coastal Bank.

The Census data, gathered in April, effectively ignores the summertime boom for coastal communities like Hull and Brant Rock, where the population shifts most noticeably from season to season rather than on a daily commute.

Although the daytime population flux has been fairly constant since the last available data in 1990, patterns could change. The Greenbush commuter rail, scheduled to begin service in 2007, could offer an alternative to the crawl up Route 3; state initiatives like ''smart growth" encourage developments, such as the reuse plan for the South Weymouth Naval Air Station, where people can live, work, and shop in one place; and some towns have worked to revitalize their business communities to alleviate the tax burden on homeowners.

But Phillip Salobeck, a demographer in the population division of the Census Bureau, said the data also tells another story:

While come communities might clamor for more commercial enterprise, Salobeck said, others ''might say: 'Yeah, I live in a bedroom community and I'm proud of it -- and I want to keep it that way.' "

Carolyn Y. Johnson can be reached at cjohnson@globe.com.