PORTLAND, Maine — Traffic has dropped for a second month at the Portland International Jetport after 16 consecutive months of growth.

Monthly passenger traffic at the airport peaked at 200,000 in August, but it has been downhill in the two months since then. Last month, 151,384 passengers used the airport, compared with 159,678 the year before.

The declines would be worse without the arrival of low-cost carriers in Portland. JetBlue arrived in Portland in May 2006 and AirTran Airways in June 2007.