Optimizing search through large list of lat/long coords to find match

Question

I need to create a page that

1. takes 2 addresses (to and from),
2. plots the route AND areas within 1 mile of this route,
3. THEN figure out i

Answer 1

You can use a spatial index and search for a 2d range,i.e. bounding box. For example with the MySQL spatial extension. You can also try my hilbert curve class (phpclasses.org) it uses a quadkey with a range search and it's a pure php solution. You can also try a quadtree it has some better perfomance over a r-tree.