The alert comes at what is usually the beginning of the high season for travel from the United States to Europe. It's not the time of year that those who make their living off of the travel industry want to see the State Department issuing destination alerts.
"May and June are really big months. We'll see how it plays out but so far everybody's still planning to travel," said Sona Tazian, European Sojourns.
The alert is unprecedented in its scope. Applying to the entire continent, the State Department said "terrorist groups continue to plan near-term attacks throughout Europe, targeting sporting events, tourist sites, restaurants and transportation."
Tazian said that ultimately, people need to do whatever feels right for them, but urges travelers to make an informed decision.
"Nobody is saying don't go to these places, it's just be aware, once you're there," Tazian said.
In fact, according to a survey conducted after the Paris attacks late last year, only 10 percent of travelers cancelled a booked trip in response - although 22 percent chose to delay booking and 18 percent switched to a safer destination.
"I can't control anything. So I don't worry about it. I just travel. Be alert and watch out for what you can see," said Thom Blinkinsop.
At Chicago O'Hare's international terminal, where security is still tighter than usual following the Brussels bombings, that was the attitude echoed by most checking in for their European flights.
"Definitely yesterday it raised alarm. Worried me a little bit. But no. I don't think anything's going to happen. It's a one in a million chance," said Peyton Kimes.
Chicago's only non-stop flight to Brussels was canceled Wednesday as the airport there remains closed.
EMANUEL CONSIDERING TERRORISM IN SUPERINTENDENT SEARCH
Mayor Rahm Emanuel was asked Wednesday if the attacks in Brussels would change his approach to selecting a new police superintendent.
He talked about his priorities, saying public safety, reduction of gun violence and gang conflicts were at the top. But the mayor said it's important to have someone who is "conversant" on the issue of terrorism.
"If you're the mayor of a big city, global events, terrorism is there, is present and it's part of the things you're evaluating," Emanuel said.
Last week, the Chicago Police Board sent the mayor three finalists for the job: Cedric Alexander, Anne Kirkpatrick and Eugene Williams.
DEPAUL, U OF I STUDENTS IN BELGIUM
DePaul University confirmed 17 students and a faculty member from DePaul University traveling in Belgium as part of a study abroad group are safe.
We are thankful to report all SPS students & faculty in Belgium for study abroad are safe from today?s attacks.Thoughts& prayers to Brussels— DePaul SPS (@DePaulSPS1) March 22, 2016
The group is staying in the city of Leuven and were headed to Brussels when they heard the news.
"We missed the train. We would have been in Brussels - on the way to Brussels - when that Metro bombing occurred. And thankfully we got to take a later train. We would have been stuck there all day and as a worst case, had we left earlier, we would have been in the same neighborhood of that bombing," said Joseph Schwieterman, a DePaul University professor.
The group is scheduled to come back to Chicago on Sunday, but they're not sure how the attack will impact their travel plans.
In addition, the University of Illinois said 57 students and faculty on study abroad programs in Belgium are confirmed safe. School officials said they are working with the State Department and closely monitoring the events in Europe.