"We're hoping it won't be a problem," acting Streets Commissioner David Perri said.
The program will not affect evening rides that will continue from 6 to 10:30.
Councilman Mark Squilla said he introduced the proposed changes last month to help fill the void of afternoon tourist activities after federal budget cuts forced many historic buildings to shut down, like the Declaration House, or close early.
Squilla said City Council would not vote on whether to make the change permanent until results of the pilot program are in.
Cutting off early carriage rides denied tourists who needed a rest or who missed getting tickets to attractions and wanted to visit the historic area, said James Cuorato, president and CEO of the Independence Visitor Center.
Several carriage drivers said business in the summer starts picking up around 3 p.m. after tourists visit attractions like the Liberty Bell and the Betsy Ross House.
"We wanted to go later," said Shannon Dorer of Harrisburg as he hopped onto a carriage just before the 3 p.m. cutoff in place last week.
He said they would have preferred to go at 4 "just because we wanted to do the rest of the touristy stuff before that closed."
Although carriage companies are hopeful the increased hours will help business, some residents worry it will pose traffic and safety concerns for the horses and pedestrians.
"The neighbors who live on those streets are going to be concerned about traffic, they cause a good amount of traffic delay when they walk so slowly in the lanes," said Steve Weixler, president of the Society Hill Civic Association.
Contact Summer Ballentine at 215-854-2000 or at SBallentine@philly.com. Follow her on Twitter @esballentine.