How did Wyoming get its nickname Big Wyoming?

Wyoming is known as "Big Wyoming" or "Big Wonderful Wyoming" or "Wonderful Wyoming".  All three are phrases used to promote Wyoming.  The "Big" comes from the fact that Wyoming is the 10th larges US state in area.
Wyoming is known as "Big Wyoming" or "Big Wonderful Wyoming" or "Wonderful Wyoming".  All three are phrases used to promote Wyoming.  The "Big" comes from the fact that Wyoming is the 10th larges US state in area.