The Cajuns of south Louisiana developed both a distinct dialect/patois and a very, very strong accent.

The Cajuns arrived in Louisiana penniless, and most were not given a hefty land grant. They arrived with literally nothing but their lives. Upon arrival, most of them found that the only help they could get was from those considered at the lowest of the social hierarchy: First Nations, free people of color, etc. These kind people showed the Cajuns how to survive in the hot, humid climate, and how to utilize food sources that weren't imported from Europe. Some of our traditions and 'unique' foodstuffs used even today directly stem from those early interactions. (Okra and file', I'm looking at you.)

Poverty and social spurning forced the Cajuns to go further into the unsettled regions of the Louisiana territory, although they tended to stay close to the waterways and shores which they knew in their native Arcadia. They tended to settle in specific areas, places where the land was considered inferior, worthless, not immediately accessible to trade/commerce, etc.: the swamps, the south Louisiana prairies, scrubland, shallow coastal islands, etc.

These settlements were self-supporting, and thrived into prosperity, all in a place where "normal" habitations of the time would have failed. Birth, adulthood, marriage, children, and death all occurred within the settlement. The Cajuns had their own churches, stores, markets, etc. The old Acadian traditions, recipes, and language survived, but of course they evolved over time. Due to a continued social stigma that saw Cajuns as backwoods and inbred, the settlements were maintained over several centuries. It was "safe", and even used as a haven by escaped slaves and Native Americans on the run.

The "breaking up" of these settlements occurred after WW I under the governorship of Huey P. Long, when it became mandatory for all children, including Acadian children, to attend school, which were mandatory English-speaking. Most of these kids spoke zero English, so they were both exposed to the blatant prejudices of "Anglo" children, and physically disciplined for speaking French at school. During WW II, many Cajuns either left the settlements to work in wartime efforts such as shipyards due to the very high pay, or they went into the Armed Forces, where they were used extensively as French translators. The old settlements became 'diluted' with those of Anglo, Irish, and other ethnic origins.

By that time, our French had evolved into a distinct patois, a mix of French, Native American, and English words. Today, most of us are bilingual, but our native language is still spoken by many, and if you hear the English, you'll wonder if you're really hearing English at all due to the thick accent. The French? I've heard a speaker of Parisian French once describe it as a fascinating delving into 18th century French. Our language, and our entire culture, is unique because of the prejudices of the past. What was once a shameful thing has become an ethnicity in which the state takes pride. Go figure, comme sa?

Source: Je suisse Acadienne. I'm a Cajun.