What is the name given to the actual original pieces of paper upon which the amendments, for example the 14th Amendment, are written?

Dear John -- thank you for posting on History Hub!

Amendments to the Constitution of the United States proposed by U.S. Congress are in the form of joint resolutions. Depending on the chamber of origin, joint resolutions begin with a designation of either H.J.Res. or S.J.Res.

To use your example of the 14th Amendment, the Joint Resolution Proposing the Fourteenth Amendment of the United States Constitution in the National Archives Catalog is the original enrolled joint resolution.

When a bill or a resolution is enrolled, that means it's passed both the House and the Senate and has been prepared in its final form. Enrolled bills or resolutions are signed by the presiding officers of the House and the Senate.

For more detail on the amending process after Congress has passed a joint resolution, please see the NARA website on the constitutional amendment process.

Cheers!

Sarah