Chapter, Patner, Affilliate and At-Large Area Map

I do a little GPS work for the American Discovery Trail Society from time to time.  I've been working on a map of the Buckeye and North Country Trail chapter, partners, affiliates and ADTS state committees from the perspective of the public wanting to join them.  It's an Ohio thing.    There's some nuts, bolts and assumptions that were necessary to make it.  I had to get the parking data for the American Discovery Trail in Indiana on the North Midwest Route done so I can measure the driving time between that and the west chapter-less area of the North Country Trail - Ohio and ADT - IN NMR.  Once complete, I'll have to alter the BT's Far SE Ohio for the present situation and possibly do some minor work on the map for it's Miami River's Chapter?

Recently, I charted that Detroit and parts of Ontario, Canada were closer to the BT's northwest chapter-less area.  But I didn't take into account the addition of the new Iron Belle and Trans Canada Trails.  I corrected that.  With the addition of those two, the BT's NW chapter-less area only has an advantage in a handful of zip codes in Monroe County, Michigan now.

If you go on the website for the United States Postal Service, you can enter your address and get the locations for the nearest 3 post offices.  I have no idea if some online service exists that could be programmed with trail parking areas and take an address input from anywhere in North America, or the world for that matter?  I don't even know what to look for?

My map could be deployed on Google and embedded into a website.  It won't do the world, but it will do Ohio and some of the vicinity.  I did it according to driving time from wherever Google locked on to a zip code to the nearest trail parking area.  The section with the parking area that had the least amount of driving time was awarded the zip code.  I didn't have to do every zip code in Ohio and vicinity.  Instead, I figured out a faster way.  I used county and zip code GIS shapes.  All I had to do was determine the separation point and color the shapes for their respective areas.  Once I got that, logic took over and I filled in the rest quickly.

I have to be real careful with how I express this.  I have absolutely no authority to put boundaries on these chapters, partners, affiliates and chapter-less areas.  That's internal and this project's intent is the public, or external.  I know of possible new additions that I can't get into now, but my map will need to have variations that compensate for them ahead of time.  And if I'm to report to the BTA about my findings, I'll also need to tally their populations.