JetBlue is adding another roundtrip flight between Boston and Baltimore in the spring, the airline announced Monday. This will mean JetBlue operates five roundtrip flights on the route beginning in March, which would be the same number as rival discount carrier Southwest except Southwest announced last week they were adding two Boston-bound flights in the spring. So they're staying just a step ahead of JB, which began offering the flights about the same time. Now, neither is ahead of AirTran, which has been flying to Boston for a lot longer and still offers nine daily nonstops - the most number of flights from BWI to Logan.

Spring flights on JetBlue and AirTran start at about $39 each way. Southwest starts at about $41 one-way.