cartography

arrows! [Fig 11.5]

arrows = "distributive". also radial, network
[Fig 11.6]

must be easily visible	[Fig 11.7]
but not overly dominating [Fig 11.8]

show quantities [Fig 11.11]
other ways to show flow [Fig 11.16]

[Cartography: Thematic Map Design. Borden Dent]