The Mayor of Pittsburgh will marry 20 same-sex couples in a mass wedding at Pride next month, to celebrate marriage equality in Pennsylvania.

Bill Peduto, the city’s Democratic mayor who assumed office in January, will perform a mass wedding on June 15 at Pittsburgh PrideFest.

He said in a statement: “I said last week I would be thrilled to make the marriage of an LGBT couple the first I officiate as Mayor, and being able to share that moment with many others should make for an even more joyous celebration.”

He will be following in the footsteps of the Mayor of Philadelphia, who opened his doors to perform some of the first same-sex weddings in Pennsylvania.

Pennsylvania became the 19th US state to recognise same-sex marriage last week, following days behind Oregon.

Striking down a Constitutional marriage ban last Tuesday, Judge John Jones wrote: “We are a better people than what these laws represent, and it is time to discard them into the ash heap of history.”

The state’s governor refused to appeal the ruling, cementing same-sex marriage as law.

Judge Jones later stated: “We had to assume that it might be appealed and that I might not have the last word.”

“It is remarkable when you write something as a district court and you find out within the week that it is the final decision.”