Who better to describe this coin than the issuer, the United States Mint (at www.usmint.gov):
"The 2015 March of Dimes Proof Silver Dollar celebrates the 75th anniversary of the establishment of the March of Dimes. Founded by President Franklin D. Roosevelt on the eve of World War II as the National Foundation for Infantile Paralysis, the March of Dimes was instrumental in the eradication of polio from the United States. Since then the March of Dimes’ mission has been the prevention of birth defects, working for every generation with new research and discoveries to help babies be born healthy and grow up strong.
Surcharges of $10 for each silver dollar sold are authorized to be paid to the March of Dimes to help finance research, education and services aimed at improving the health of women, infants and children.
The obverse (heads) design represents the past depicting President Franklin D. Roosevelt and Dr. Jonas Salk, two leaders in the fight against polio. The inscriptions are “LIBERTY,” “IN GOD WE TRUST“ and “2015.”
The reverse (tails) design depicts a baby cuddled in the hand of a parent, representing the foundation’s dedication to the health of babies. The inscriptions are “UNITED STATES OF AMERICA,” “$1,” “MARCH OF DIMES” and “E PLURIBUS UNUM.”"
The introductory price of this coin was $46.95 from March 13, 2015 to April 13, 2015, after which the price rose to $51.95. The Mint capped the mintage at 500,000 and there were no limits on how many could be ordered.