Why memory is divided in even and odd banks in 8086 microprocessor?

in 8086 there is 20 bit address bus,so it can address 1,048,576 address.

At each address we can store 8 bit address (1-byte)but if want to write a Word(16-bit)into a memory segment to store data in byte form then we write the data in two consecutive memory address which are even(low) and odd(high) memory.