Every summer, southwest Michigan undergoes a transformation: the weather warms, patios open and the sun appears almost every day.

Many of those attributes also happen throughout the United States in May through August, but what makes southwest Michigan different is that people from all over the country flock to the region to enjoy the many bountiful lakes.

Cass County alone has around 200 lakes and ponds, says Laurel Ward, the web designer in charge of DiscoverCassCounty.com. Most of these lakes are private, with less than a dozen public access sites.

“My own experience is from Diamond Lake, where I live,” Ward said. “I would say probably 60 to 70 percent of the population leaves the area in the winter, even though those are year-round homes. They go south to Florida, the Carolinas and Arizona, where there are warmer climates.”

According to Jim Hosking, the president of the Diamond Lake Association, there are roughly 850 homes on and around the lake, and he also believes that 70 percent of the homeowners leave for the winter. If his and Ward’s estimations are accurate, that means nearly 600 homes are empty until summer rolls around.

These homeowners likely will not show up in Census data, either, which shows that Cassopolis had a total population of 1,774 in 2010. According to Census.gov, a person’s primary residence is the “place where they live and sleep most of the time,” and most of the residents around Diamond Lake will spend more than half the year living elsewhere for tax purposes.

“Most of them are Florida residents because of the tax structure,” Hosking said. “It seems to be more advantageous to them to be Florida residents.”

According to financial websites such as Nerdwallet and The Balance, the tax advantages for a Florida resident include no individual state income tax and no state death tax (a tax on inheritance, which Michigan does not have either). In order to be deemed a Florida resident, a person must live and sleep in Florida for at least 183 days per year.

The residents also tend to be of a higher income bracket. Not only do they likely own a second home, but their homes are also often more expensive than other local residential areas.

In March 2017, the average selling price for waterfront homes was $458,667 according to Southwestern Michigan Association of Realtors. This March, that number dropped significantly to $289,909, but was still $143,272 more than the average price of non-waterfront homes.

“Diamond Lake in particular, the property values are so high that it’s not a place where young families can afford the properties,” Ward said. “There are other lakes in the area that have lower property values. They are equally good lakes, they are just not as big.”

The most expensive house on Diamond Lake currently for sale on Realtor.com is worth $2.1 million, and there are more than a dozen listed at more than $700,000. While it may seem as if the high prices on Diamond Lake are driving the average price of waterfront homes, the median prices are also very high. In March of this year. The median price of a waterfront home was $235,000, whereas it was $127,000 for non-waterfront homes.

The other lakes also get an influx of residents during the summers, says Joe Morin, the bar manager and co-owner of Sister Lakes Brewing in Dowagiac.

“Sister Lakes is essentially a resort community surrounded by a farming community, so most of the homes on the lakes are second homes, vacation homes or vacation rental homes,” Morin said. “Obviously, the nice weather brings more people to the area to stay at their second homes, or there are families who rent the same weekend or week every year and have family reunions. So the population definitely increases considerably once we get into spring and into summer.”

He says that the staff at Sister Lakes Brewing more than doubles every summer to keep up with the influx of available customers and extra hours of operation.

“In the wintertime we close a couple days a week and we shrink our hours, so we’re not open for as many days or as many hours,” Morin said. “On Wednesday, when we opened our doors, we’re now open seven days a week and we’re open at noon every day. We expand the days and the hours, but obviously that also means expanding staff, beefing up inventory.”

Morin says this is an advantage to his business, which caters itself to a diverse range customers. But the same cannot necessarily be said for Cassopolis because it has a limited number of retail and restaurant businesses.

“I don’t know how much summer residents add to the local community,” Hosking said. “I think a lot of [their shopping] occurs in Indiana.”

That could change soon, as Cassopolis and other lake areas are working to add more businesses. Ross Beatty Jr.-Sr. High School plans to open a student-run coffee shop in the future, which Hosking says the seasonal residents will likely enjoy.

“I would think that the lake residents would be interested in things like that — not having to go a half an hour away to get a coffee,” he said. “I think there would definitely be an interest in more local options in terms of restaurants, coffee shops and things like that.”