It’s July: The handsome Colonial and Greek Revival homes drip with bunting, blue hydrangeas sprout from lawns and white sails wave from Narragansett Bay. The red, white and blue stripe has been painted down Hope Street, clouds scud across sun-spangled skies and dusk explodes as a plum streaked with orange and pink.

At precisely 10:30 Thursday morning, the parade billed as America’s oldest Independence Day celebration kicks off at the corner of Hope and Chestnut as Bristol steeps a tradition that is this quintessential New England town’s secular rite.

A committee of local residents work all year for this day, raising the money, publicizing and planning the concerts, beauty pageants and parties that welcome our founding national holiday.

For many, July Fourth in these times is little more than a summer respite from toil, a chance to kick back, hit the beach or fire up the grill. In Bristol, the Fourth is a hybrid of patriotism, Old Home Week and reflection. High school and family reunions are timed for this week; an enduring theme is Bristolians who haven’t seen other since school days hugging in the street or on the Lobster Pot’s deck.

Bristol’s narrative is America’s, and particularly, New England’s. History wafts in the breezes off Bristol Harbor. The town’s colonial-era fortunes were made in the African slave trade. Reminders of that terrible legacy linger still. The Linden Place mansion, now a museum, peers over the parade. It was built with the profits of the trade in humans. DeWolf Tavern, the lovely restaurant overlooking the harbor, was once a rum distillery that bolstered the Triangle Slave Trade.

A mordant local saying is that only the best families in town can link their roots all the way back to a slave trader, rum-runner or child labor factory employer.

The biggest honor the town can bestow on a resident is to be anointed the chief marshal, who leads the parade. From 1775 until World War I, these parade leaders were a long line of Yankee Protestants. Their surnames were Colt, DeWolf, Haffenreffer, Rockwell.

Then comes the ethnic waltz of immigration. Lured by jobs in an area that was once a manufacturing lodestone, newcomers flocked to town. Soon after, Irish and Italian American surnames pop up on the chief marshal rolls—Leahy, Riccio, Campagna. The first chief marshal of Portuguese background came in 1954, when Matt Brito led the marchers. Since, many marshals have been of Portuguese lineage.

On Thursday, the scenes will be familiar. There will be toe-tapping Sousa tunes, bagpipes, floats and puppets, drum and bugle corps. The young U.S. Navy sailors will strut in their dress whites, along with older veterans in too tight uniforms. The politicians will wave and break to the sidewalks for some hihowahyahs and grip and grins. Norman Rockwell you say? Think again.

This Fourth celebration has survived wars, depressions and societal upheaval. The challenges of change hover over this year’s festivities.

In the last month, the town has been gripped by disputes over events surrounding Gay Pride Month. The town library’s decision to have a drag-queen story hour for children and a show with gay themes at the Bristol Art Museum both generated anger.

The boards of both institutions tried to shut down the events, but relented after an outcry. Bradley Wester, who recently moved to Bristol, insisted that his exhibit that included male soldiers kissing be included. Wester told The Public’s Radio he was trying to show how difficult life is for those who are gay. “I will not be censored,” he said.

The American values of tolerance and free speech prevailed, if not easily.

The slaving legacy is still debated. Some DeWolf family descendants have dug into their past and acknowledged their relatives role in the original national sin. In a book, “Traces of the Trade,” and a movie, some DeWolf family members have tried to reckon with their ancestors tortured past and the family fortunes and generations of white privilege it fostered. Yet other family members don’t like to dwell on this past.

Writer Mary Cantwell was raised in Bristol. Her memoir, “American Girl,” is a literary coming of age story set in town during the Depression and World War II.

“Early in the morning when the sky is grey,” Cantwell wrote. “We can hear the dull boom of Fourth of July canon.”

This week, the canon will fire again at dawn, as Bristol celebrates its 234th Fourth. It tells us that Independence Day is not only flag-waving congratulation, but a reminder that our national saga is one that is forever changing and forever the same.

Scott MacKay’s commentary can be heard every Monday morning at 6:45 and 8:45 and at 5:44 in the afternoon.