A rare copy of the Magna Carta held by Hereford Cathedral is to go on display in Houston, Texas.
Hereford Cathedral has lent its copy of the historic document, which dates back to 1217, to the Houston Museum of Natural Science.
The document will be on display at the museum from 14 February until the middle of August 2014.
It is being lent together with the King's Writ, dated 1215 and issued from Runnymede. It is the only known surviving example of the document issued to give local sheriffs advance warning of the impending arrival of the Magna Carta and telling them to prepare its implementation.
"We are fortunate to be custodians of these historic documents," said Canon Chris Pullin, Chancellor of Hereford Cathedral.
"As we approach the 800th anniversary of the sealing of Magna Carta in 1215, along with the issuing of our King's Writ, we are delighted to be able to share these documents with our American friends."
The Magna Carta is currently on display at Hereford Cathedral as part of its Mappa Mundi and Chained Library Exhibition, which ends on 30 September.
Canon Pullin continued: "On both sides of the Atlantic we have come to see Magna Carta as an iconic milestone on the long road of human liberties and justice. Many world leaders have been inspired by what it stands for, and we hope that this loan will strengthen the resolve of a new generation to safeguard the values of justice, peace and liberty."
It is thought that the documents have been held at the cathedral since they were first received nearly 800 years ago.
Glyn Morgan, Chief Executive of Hereford Cathedral Perpetual Trust said: "As far as we are aware, this will be the first time that either document will have left Hereford Cathedral since they were received in the early 1200s,with the exception of when they went into safe keeping during the last war and for a short time afterwards."
The loan has been negotiated by the trust following a visit to the cathedral earlier this year by trustees and staff from the Houston Museum of Natural Science.
Morgan said he hoped the loan would strengthen links between Hereford and Texas.
"We also hope that this loan will build on the many other links between Herefordshire and Texas which, of course, can be traced back to when the Hereford breed of cattle was used by settlers," he said.
"More recently, one of the Texan bishops stayed in Hereford ahead of the 2008 Lambeth Conference and since then there have been increasing diocesan links."
An estimated 1.5 million people are expected to see the Magna Carta during its display at the museum, which forms part of an extensive education project.
"We are very honoured to be the museum for which Hereford Cathedral has elected to share this precious document with Houstonians and many others in Texas and the US," said Joel Bartsch, President of the Houston Museum of Natural Science.
"To be able to put on display and unite for the first time a copy of a Magna Carta and of the King's Writ in the United States, two documents that helped shape many other landmark documents including our US Constitution, is a momentous occasion for Houston Museum of Natural Science."
There are four surviving original copies of the Magna Carta, two of which are held at the British Library, and one each at Lincoln and Salisbury Cathedrals.
Plans are being put together to bring the four originals together for the first time in history at the British Library as part of commemorations in the UK and around the world to mark Magna Carta's 800th anniversary in 2015.