CHICAGO — Last weekend Quincy, Ill., Mayor Kyle Moore drove across the Mississippi River to Hannibal, Mo. He pulled into a popular brewery, the parking lot crammed with familiar cars, all with Illinois plates.

“You can’t get into the place,” he said. “They’ve been running out of food.”

Watching the taillights fade across the border is a common source of aggravation for public officials in communities throughout Illinois. For many, it has only gotten more worrisome as limits put in place to contain the novel coronavirus are loosening in every surrounding state, while Illinois remains mostly closed.

Five neighboring states — Wisconsin, Iowa, Missouri, Indiana and Kentucky — have all in recent weeks relaxed or abolished restrictions while Gov. J.B. Pritzker (D) has twice extended Illinois’s stay-at-home order.

In daily briefings, Pritzker frequently warns residents of the public health risks of crossing the border to states like Iowa, which allowed restaurants to open this month. There, as in all neighboring states, social distancing is not required, precautions are largely up to individual store owners, and images of crowds cramming the shopping aisles and parking lots of big-box stores have proliferated online. The differing rules have alarmed Pritzker.

“People who are traveling across the border and . . . gathering in large groups and who are going into restaurants or bars . . . will asymptomatically come back to Illinois and spread it,” he said recently.

Illinois has the third-highest number of coronavirus cases nationwide, behind New York and New Jersey. More than 105,000 residents have tested positive, and more than 4,700 have died.

Pritzker has said he is not willing to rush to loosen restrictions with numbers still rising and federal efforts on testing still lagging. Nonessential businesses remain closed in Illinois, and face coverings are required in all stores and other public settings.

The third phase of the state’s reopening plan will start May 29. Gatherings of up to 10 people will be allowed, and salons, health clubs, offices and some manufacturing may open, with restrictions. Pritzker said this week it appears that the majority of the state is ready to move forward with reopening.

Illinois will still be far behind neighbors like Indiana, which will allow gatherings of up to 100 people starting this weekend, and Missouri, which never required businesses to close. Last week the Wisconsin Supreme Court struck down Democratic Gov. Tony Evers’s extension of his stay-at-home order, ending two months of restrictions.

The lack of coordination among the states has officials in Chicago worried about a surge in cases and deaths this summer.

“They are going to bring it back here; it’s a grave concern,” said Alderwoman Susan Sadlowski Garza of the city’s 10th Ward, which borders Indiana.

Garza said she recently drove over the state line and saw crowds gathered outside restaurants. No one was wearing a mask, she said, and she felt helpless and upset.

Nearly 40,000 of the state’s cases have been in Chicago.

“I have to surrender to the fact that people are going to do what they want to do. I can get the word out, I can distribute masks, I can give people resources,” she said. “But there is only so much I can do when people think the right thing to do is to go to a restaurant or bar in Indiana and come back home.”

The pandemic is seen less as a public health emergency and more of an economic one in downstate and more rural counties. The impulse to cross a bridge to another state without taking precautions is purely psychological, said Chris Lain, mayor of Savanna, a northwest Illinois river town of about 3,000 people.

“When you watch the national news, it’s all about the massive amount of cases in Chicago and Cook County. But we’re not seeing that. In this area, we’re only seeing our small businesses suffering,” he said.

Lain said one of the biggest challenges is that the Illinois side of the river is dependent on Iowa. Most of the chain stores are in Iowa, and people have friends and family on both sides. He would often see people practicing social distancing and wearing masks in Savanna when the pandemic started. That changed in late April, when Pritzker extended the stay-at-home order.

“Less people are taking it seriously. There’s a lot more defiance,” Lain said.

Many businesses suffered over the winter, he said, and then went straight into the shutdown, leaving reserves tapped.

The state’s reopening plan breaks Illinois into five areas. Each must have no overall increase in coronavirus cases over 28 days. Moore, the Quincy mayor, fears that the plan could have a reverse effect on public health, with people tired of being at home heading into large crowds in states that have reopened. He believes that communities like his are unfairly restricted, despite having minimal cases. There have been 43 coronavirus cases in Adams County, which includes Quincy, and one death.

“People feel they are penalized because Chicago has such a high disease burden,” Moore said.

Pritzker said Friday that caution is needed because “it’s still unclear where we’re going to see a spike . . . over the summer.”

The ultimate reopening of the state, he said, “will be guided by the science and the data, and it’s unclear because, as you move forward, the science is evolving and the data is giving us more information on what we ought to be doing.”

Many businesses over the border are welcoming the influx of people — and money — from Illinois. At Jimmy’s Pancake House in Bettendorf, Iowa, customers go through temperature checks at the door and are seated at safe distances from one another. That hasn’t stopped the rush, said owner Manny Kardaras.

“Everyone is looking to find somewhere to eat. The public sentiment around here is everybody is just tired of being stuck in their house,” he said.

In Gresham, Wis., Annie Retzlaff operates a 200-site campground with an outdoor pool and abundant nature. Retzlaff, who stayed open in defiance of Evers’s stay-at-home order, thinks coronavirus is “overblown.” She said that summer is “going to be awesome” and that reservations are filling up, many from her Illinois regulars.

“Those of us who want to continue life and living and have fun and go outside, that’s what we are going to do,” she said.

Sam Toia, president of the Illinois Restaurant Association, said he is pleased that Pritzker is being so deliberate with his reopening plan. Toia said his biggest fear is that the economy would quickly reopen — only to close again if cases spike.

“That would be the death of the hospitality industry,” he said.