The difference was visible at the American Airlines Terminal B.

Outside, the terminal is quiet—the garage is closed indefinitely and curbside check-ins are no longer allowed.

Inside the airport, a state trooper dressed completely in black—long-sleeved shirt, pants, holster and combat boots—stands in line at Dunkin Donuts, while a woman with a “U.S. Marshals” jacket walked briskly past.

At about 10:00 a.m., the line to check baggage is about a 100 yards long. Each passenger’s bag is subject to an x-ray in a newly-purchased $50,000 machine before it can be checked.

And in front of the security gate, a sign reads “Attention: beyond security checkpoint all persons may be subject to random searches, ID verification and ticket verification.”

As passengers walk through, they juggle baggage, tickets and photo ID.

Although the lines are long, passengers say they are comforted, rather than frustrated, by the highly visible security.

A group of four Boston residents waiting for a flight to San Jose for a friend’s honeymoon chat about the bomb-sniffing dog that passed by a few minutes before.