Sonoco Products Company announced that it will permanently close its uncoated paperboard (URB) mill operations in Sumner, Washington effective immediately.  The mill has been in operation since 1915 and owned by Sonoco since 1980.  It has a capacity of 40,000 tons per year.  This decision was made as part of Sonoco?s ongoing strategy to optimize its mill network and lower operating costs.  Current customers will continue to be served from other Sonoco mill operations.  The closure is expected to impact 55 employees and Sonoco will offer severance benefits to the impacted employees.