Our depreciation expense was $20,285 in 2019, $20,083 in 2018 and $19,761 in 2017. Depreciation expense included amortization of software totaling $3,313 in 2019, $3,092 in 2018 and $2,810 in 2017.

In 2017, as a result of planned fiber deployment, we recorded a noncash pre-tax charge of $2,883 to abandon certain copper assets that we did not plan to utilize to support network activity. Largely due to the pace at which our customers have migrated to fiber, which exceeded previous forecasts, we identified additional copper assets that we no longer expect will be utilized to support future network activity. In the fourth quarter of 2019, we recorded a noncash pre-tax charge of $1,290 to abandon these copper assets. Each of these abandonments is considered outside the ordinary course of business.