YANKTON, S.D. (AP) - TransCanada Corp. officials say work should start by mid-October on the Keystone crude oil pipeline's Missouri River crossing.

TransCanada spokesman Jeff Rauh told the Yankton City Commission in South Dakota that the crossing would take six to eight weeks to complete.

Preliminary work began early this month in northern South Dakota on the pipeline, which will carry crude oil 220 miles through the state's eastern tier of counties. Pipeline construction is already under way in eastern North Dakota.

Rauh says TransCanada wants to make sure the river crossing is done well before the pipeline construction approaches from the north.

Officials say Yankton is the only community that will have construction inside its city limits.

The buried pipeline will carry crude oil from Alberta, Canada to refineries in the U.S.