PORTLAND, Maine — The final compromise highway spending bill approved by the House and Senate preserves federal subsidies for the Downeaster, which runs between Portland and Boston.

Sen. Olympia Snowe, who included language to keep funding for the Downeaster in the Senate bill, says the Portland-to-Boston service is critical in attracting commuters and tourists and “has time and again proven itself as an indispensable economic boon for Maine.”

The bill, which received final approval Friday in both chambers, now goes to the president’s desk.

The Downeaster transports more than a half million passengers a year between Portland and Boston, and this fall the service will expand northward to Brunswick.