CHICAGO (CBS) — Church closings could be in the future for the Roman Catholic Archdiocese of Chicago.

Archbishop Blase Cupich talked to about 600 priests Tuesday at the Drury Lane conference center in Oakbrook Terrace. A source said topics discussed included possible church closings.

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The source said the archdiocese is considering “clustering” – closing some parishes from one general area, and linking the closed churches with another parish that remains open.

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The archdiocese has 353 parishes in Cook and Lake counties. The archdiocese said determining factors into which churches would close ultimately include weighing how many priests the archdiocese has to celebrate Masses on Sundays against the number of people in the pews.

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A source said it was not spelled out at Tuesday’s meeting exactly how many churches might have to close, but it was pointed out the greatest percentage of active priests are 61 to 70 years old, and are closing in on retirement. Only 3 percent of active priests in the Chicago archdiocese are 26 to 30 years old.