  A conjecture of Erd\H{o}s, Graham, Montgomery, Rothschild, Spencer and Straus
states that, with the exception of equilateral triangles, any two-coloring of
the plane will have a monochromatic congruent copy of every three-point
configuration. This conjecture is known only for special classes of
configurations. In this manuscript, we confirm one of the most natural open
cases; that is, every two-coloring of the plane admits a monochromatic
congruent copy of any $3$-term arithmetic progression.
