Energy supplier Constellation, owned by Chicago-based Exelon, also is keeping its downtown offices open, but "employees have been advised to discuss alternative work arrangements with their supervisors as necessary," spokeswoman Kelly Biemer said in an email.

Verizon's office at 1 E. Pratt St. has been mostly empty since Wednesday, after employees were told they would not be able to get into the parking garage after 7 a.m. that day, said Sandy Arnette, a spokeswoman. The office's workers have settled temporarily at area Verizon offices or worked from home, she said.

"We are in the center of the racetrack, and you can't get access to the garage," Arnette said. But thanks to laptops and smartphones, "we can get our jobs done anywhere."

Usha Salon & Day Spa on East Fort Avenue in Federal Hill no longer tries to stay open during Grand Prix weekend.

"We tried to remain open once, and it was a mess," said Gayatri Gupta, an owner. "To start with, our staff couldn't get in. It was a mess for them to get in, and then the customers couldn't get in. It was not worth it for us to keep the business open and go through that expense."

The salon will close more than an hour early on Friday, around 6 p.m., and not open at all on Saturday.

Race patrons must submit any bags brought into the course for searches by guards manning the entrances, a new measure prompted by the Boston Marathon bombing, but that's about it for new security, Mayer said.

"This event isn't as porous as an event like a marathon, obviously, and we felt good about our existing plan," he said. "That being the case, we're still going to have people being not too shy about looking through the bags carried in."

J.P. Grant, the Columbia financier who shouldered the financial burden of running the race, spent part of Thursday walking the streets and talking with potential customers. Grant has said he expects to lose money on the race again this year, but not as much.

The future of the race depends on increased revenue and finding a date to run in the coming years. Events scheduled for M&T Bank Stadium and the Baltimore Convention Center in 2014 and 2015 have pushed the race from Labor Day, and Grant is working to find another weekend that could work.

"We're going to work it out," Mayer said. "Is there a percent chance that we can't find a date? Sure. But I really think that once we sit down and have all the facts, we will find a time to run it."

On Thursday, Mayer addressed a group from New Jersey involved in trying to plan a Formula One race in Weehawken, N.J., explaining the complicated web of entities involved in putting on Baltimore's Grand Prix. The New Jersey group has struggled with many of the same issues that have hindered the race here: lack of financing, public opposition and the need for sponsorship dollars.

"You guys know it. You can't just say there's going to be a race," he said. "There's so much to deal with. But it can be incredibly rewarding."

Baltimore's race has taken a "quantum leap" toward fulfilling the promise that city leaders saw when they approved the race in 2010, Mayer said. A year ago, he spent the Thursday before the race scurrying around the site, checking every facet of the operation. His slower place this year shows the race operation can continue to evolve and become less difficult for the city, he said.

Grant said he'll watch this year's event with clear eyes. For a businessman with no experience in racing — or running a big-time sports event — last year was bewildering. He now feels better able to evaluate whether the Grand Prix is right for the city.

"Hey, you've got to try things," Grant said. "This city has so much to work with. It has so much promise. So let's try things like this. Let's see what we can build."

Baltimore Sun reporter Lorraine Mirabella contributed to this article.

Baltimore Grand Prix 2013 news from The Baltimore Sun