X- the great leveler for November 24

The first X, introduced in 1827 by George Shillibeer for a ___ ___ at Abney Park in Stoke Newington, north-east of London (UK), was designed ___ ___ 25 children.

R:G:B :: 255:216:0

In April 1939, Dr. Frank W. Cyr, a professor at Teachers College, Columbia University in New York organized a conference that established national X construction standards for the U.S., including the standard ___ ___ ___ the X. It became known officially as "National X Chrome." The ___ was selected because ___ ___ ___ ___ ___ ___ easiest to see in the semi-darkness of early morning.

Glean X from the 3 clues above. Happy Thanksgiving!