River travel is the primary means of local transportation in the summer.
They aren't using it as a primary means of communication.
The stock exchange here is the primary means for Chinese companies to raise capital.
Over 13 million people use the public transit system daily as their primary means of travel.
The system is students' primary means of contact with the faculty.
This long range attack becomes his primary means of defense.
Walking is still the primary means of land transport around the community.
These conditions might have been appropriate a century ago when the post was the primary means of communication.
This left the river as the primary means of long distance transport.
Expertise in a field has become a primary means for an invitation onto a board.