The data displayed on these pages represent a network of star systems.
Each pair of star systems directly connected by a hyperspace route represents a dyad to which a travel time was assigned. The galactic network represents 1615 dyads of 1413 star systems. The travel time between any two systems represents the sum of travel times for the weighted shortest path of dyads between those two systems.
In regard to deciding what time distance exists between two systems; where available I have used official sources. Where these were not, I ball-parked what I thought was right. Considering that going from Bonadan, at one end of the Hydian Way, to Terminus, on the other, takes only 18 days, I may have estimated too short. Still, Tatooine to Alderaan takes eight and a half days, rather than seven hours, and Coruscant to Alderaan takes 70.5 hours, rather than 16. At any rate, I may revisit those times; but not anytime soon.
These pages and were created, and most of the data compiled and formatted by Michael Wright. Many thanks to Andrew Zavadin for hosting and Nathan Rule for data entry. Thanks also to Tore Opsahl for creating the network analysis package, tnet, that made the shortest-path network matrix possible. All but a few of systems and hyperroutes are drawn from The Essential Atlas, by Dianel Wallace and Jason Fry, which you really should go out and buy right now. In fact, here is the amazon.com link, so you can do so. The background map was drawn by Modi. The magnificent Wookieepedia was also beyond invaluable, as it already had many of the trade routes listed with the planets in order. Copy and paste are wonderful things. Further sources were different supplements/adventures published by West End Games, who made really cool stuff and are greatly missed.
Most of the credit, of course, belongs to George Lucas for creating (and owning the rights to) the Star Wars Universe, who I know has reserved all rights and all that legal stuff. I'm just happy for the opportunity to play in his sand box.