Q: Is it possible to determine how many jobs will be created if the pipeline from Canada to Texas is approved?

— Jim Dillon, Atlanta

A: It's unknown exactly how many jobs would be created by the construction of the Keystone XL Pipeline, which would connect oil fields in Alberta, Canada, to Texas refineries. TransCanada, which owns the project, has repeatedly revised its estimates. It started at 13,000 temporary construction jobs in 2011, revised it to 20,000 later that year, went back to 13,000 in 2012 and changed it to 9,000 earlier this year, according to Ellen R. Wald, a oil industry historian who reported the figures in an article for Forbes. The U.S. government put the number at between 6,000 and 6,500 construction jobs. The Global Labor Institute at Cornell's College of Industrial and Labor Relations released a study that found that between 2,500 and 4,500 construction jobs would be created. A U.S. State Department study stated only 35 permanent maintenance and inspection jobs would be created after the completion of the pipeline. Jobs likely would be created in other areas, such as service industries, steel manufacturing, refining, chemical manufacturing, petroleum transportation and petroleum dependent manufacturing. But those numbers are "impossible to estimate because so many variable(s) effect the process," Wald wrote in her article. President Barack Obama said in June that the construction would create "maybe 2,000 jobs" and there would be "between 50 and 100" permanent jobs once its built. The Keystone XL Pipeline would go through Montana, South Dakota, Nebraska, Kansas and Oklahoma before ending in Houston.

Andy Johnston wrote this column. Do you have a question about the news? We’ll try to get the answer. Call 404-222-2002 or email q&a@ajc.com (include name, phone and city).