Note 18. Segment Information We manage our business based on the products we manufacture. Accordingly, our reportable segments correspond to our principal product lines: market pulp, tissue, wood products, newsprint, and specialty papers. None of the income or loss items following  Operating income (loss)  in our Consolidated Statements of Operations are allocated to our segments, since those items are reviewed separately by management. For the same reason, closure costs, impairment and other related charges, inventory write-downs related to closures, start-up costs, gains and losses on disposition of assets, as well as other discretionary charges or credits are not allocated to our segments. We allocate depreciation and amortization expense to our segments, although the related fixed assets and amortizable intangible assets are not allocated to segment assets. Additionally, all selling, general and administrative expenses are allocated to our segments, with the exception of certain discretionary charges and credits, which we present under corporate and other. In each of 2018 , 2017 and 2016 , no assets were identifiable by segment and reviewed by management. Information about certain segment data for the years ended December 31, 2018 , 2017 and 2016 , was as follows: (In millions) Market Pulp (1) Tissue (2)(3) Wood Products (4) Newsprint Specialty Papers Segment Total Corporate and Other Total Sales 2018 $ 1,085 $ 130 $ 823 $ 907 $ 811 $ 3,756 $  $ 3,756 2017 911 81 797 842 882 3,513  3,513 2016 836 89 596 1,009 1,015 3,545  3,545 Depreciation and amortization 2018 $ 27 $ 15 $ 32 $ 66 $ 47 $ 187 $ 25 $ 212 2017 31 5 33 66 45 180 24 204 2016 37 5 31 74 45 192 14 206 Operating income (loss) (5) 2018 $ 172 $ (30 ) $ 169 $ 74 $ 40 $ 425 $ (46 ) $ 379 2017 79 (6 ) 186 (23 ) (9 ) 227 (185 ) 42 2016 37 (10 ) 69 (16 ) 19 99 (117 ) (18 ) Capital expenditures 2018 $ 53 $ 27 $ 37 $ 18 $ 16 $ 151 $ 4 $ 155 2017 12 101 9 6 20 148 16 164 2016 20 156 23 2 23 224 25 249 (1) Inter-segment sales of $39 million , $36 million and $33 million , which are transacted at cost, were excluded from market pulp sales for the years ended December 31, 2018 , 2017 and 2016 , respectively. (2) The operating results of our Calhoun tissue operations, previously recorded under corporate and other, have been recorded in our tissue segment since April 1, 2018. (3) Tissue capital expenditures in 2017 and 2016 consisted almost entirely of expenditures for the tissue manufacturing and converting facility in Calhoun. (4) Wood products sales to our joint ventures, which are transacted at arms length negotiated prices, were $26 million , $20 million and $17 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. (5) In the first quarter of 2018, we changed our presentation of operating income in accordance with FASB ASU 2017-07, to present only the service cost component of net periodic pension cost and OPEB cost in operating expenses (together with other employee compensation costs arising during the period). The non-operating pension and OPEB costs, presented under corporate and other, are reported separately outside any subtotal of operating income. Prior period amounts have been reclassified to conform to the 2018 presentation. See Note 2. Summary of Significant Accounting Policies  New accounting pronouncements adopted in 2018  ASU 2017-07 Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost for more information. Sales are attributed to countries based on the location of the customer. No single customer, related or otherwise, accounted for 10% or more of our 2018 , 2017 or 2016 consolidated sales. No country in the Other countries group in the table below exceeded 2% of consolidated sales. Sales by country for the years ended December 31, 2018 , 2017 and 2016 , were as follows: (In millions) 2018 2017 2016 United States $ 2,581 $ 2,387 $ 2,464 Foreign countries: Canada 513 517 428 Mexico 148 126 126 Other countries 514 483 527 1,175 1,126 1,081 $ 3,756 $ 3,513 $ 3,545 Certain long-lived assets by country (comprised of fixed assets, net, water rights, net, energy contracts, net and other assets) as of December 31, 2018 and 2017 , were as follows: (In millions) 2018 2017 United States $ 650 $ 790 Canada 1,103 1,143 $ 1,753 $ 1,933