(Associated Press) (Associated Press)

The start of weekend MARC rail service between Washington and Baltimore on Saturday means Amtrak will no longer honor MARC passes on some of its weekend trains, an Amtrak spokeswoman said Thursday.

However, Amtrak will continue to accept MARC weekly and monthly passes on six weekday regional trains, spokeswoman Kimberly Woods said.

“Amtrak is moving away from cross-honoring arrangements with commuter operators where it no longer makes sense,” Woods wrote in an e-mail.

Amtrak ended such weekend arrangements with all other commuter rail systems “a number of years ago,” Woods said.

The weekend deal with MARC ends Saturday, when weekend MARC service is scheduled to begin on the Penn Line between Washington’s Union Station and Baltimore’s Penn Station. MARC officials say trains will run nine round-trips on Saturdays and six round-trips on Sundasy.

The weekend MARC fares — $7 each way between Union and Penn stations — are the same as weekday fares, Maryland officials said.