What is the longest distance between any two place on earth?

The longest distance between any two place on earth is about 24,901 miles (40,008 km) 

source https://distanciaskm.com/

The favorite answer is ridiculous.  The Earth is 24, 901 miles in circumference  Going ALL the way around would put yourself an the same place you are NOW. ----Halfway around is the farthest distance between points---about 12,500 miles.---after that you get closer again from the other direction.  ---Unless you drill through the CENTER of the earth, Then you only have around 8,000 miles to go.

From your location until exactly  1/2 the circumference , if you go further then the distance is shorter if you just go the opposite direction

on a road in the rain, in the dark with an empty gas can..

From the coordinates (0,0) to (0,180)

That is half way round the Equator. 

Because of centrifugal force(rotation), the Earth is slightly 'fatter' at the Equator , that round the poles.  So at the Equator measure 180 degrees , nd that is the longest surface distance on the Earth. 

Any other hemi-spherical arcs are slightly shorter. 

For navigation purposes always use a hemi-spherical arc, because that is the shortest distance across th surface of a sphere.  The meridians/longitudes are hemi-spherical arcs, but lines of latitude , except the Equator, are NOT hemi-spherical arcs.  

 From North-Pole to the South Pole, it is 12,440.01 mi (20,020.26 km)

since the diameter of the Earth is about 40,000 km the longest distance between any two places on Earth is about 20,000 km.( in a straight line).

However, if by road or sea it can be a bit further.

ps, Technically , even if a place is within a stone's throw away it can be the longest distance by travelling away from it and continuing the 40,000 km  all the way around the world until you get there.

3,278,687,297.4 miles - if you follow the prescribed zig-zag path. 

On the surface, about 20,037.508 km, half-way around the equator. If you measure straight through the center, then it's 6378.137 km.

About 7,918 miles.