Sales in the three months ended June 30, 2019, decreased compared to the same period in 2018 primarily due to the loss of sales from our former U.S. steel food and steel aerosol business, which was divested in the third quarter of 2018, the conclusion of the South America segment’s end sales associated with the Rexam acquisition and unfavorable exchange rates for our Europe segment, partially offset by higher volumes in our beverage packaging segments and increased sales in our aerospace segment. Net earnings for the three months ended June 30, 2019, increased compared to the same period in 2018 primarily due to higher volumes in our beverage packaging segments, lower business consolidation costs and lower income tax expense, partially offset by the conclusion of our South America segment’s end sales agreement associated with the Rexam acquisition, unfavorable U.S. aluminum scrap rates and increased start-up costs in our North and Central America segment.
Sales in the six months ended June 30, 2019, decreased compared to the same period in 2018 primarily due to the loss of sales from our former U.S. steel food and steel aerosol business, which was divested in the third quarter of 2018, the conclusion of the South America segment’s end sales associated with the Rexam acquisition and unfavorable exchange rates for our Europe segment, partially offset by higher beverage can unit volumes and higher pricing for our Europe and North and Central America segments and increased sales in the aerospace segment. Net earnings for the six months ended June 30, 2019, increased compared to the same period in 2018 primarily due to higher beverage can unit volumes, lower business consolidation costs and lower income tax expense, partially offset by the conclusion of our South America segment’s end sales agreement associated with the Rexam acquisition, unfavorable U.S. aluminum scrap rates and increased start-up costs in our North and Central America segment.
Cost of Sales (Excluding Depreciation and Amortization)
Cost of sales, excluding depreciation and amortization, was $2,428 million and $4,681 million for the three and six months ended June 30, 2019, respectively, compared to $2,484 million and $4,721 million for the same periods in 2018. These amounts represented 80 percent and 81 percent of consolidated net sales for the three and six months ended June 30, 2019, respectively, and 80 percent of consolidated net sales for the three and six months ended June 30, 2018, respectively.
Depreciation and Amortization
Depreciation and amortization expense was $171 million and $341 million for the three and six months ended June 30, 2019 compared to $178 million and $358 million for the same periods in 2018. These amounts represented 6 percent of consolidated net sales for the three and six months ended June 30, 2019 and 2018.
Selling, General and Administrative
Selling, general and administrative (SG&A) expenses were $111 million and $238 million for the three and six months ended June 30, 2019, respectively, compared to $127 million and $239 million for the same periods in 2018. These amounts represented 4 percent of consolidated net sales for the three and six months ended June 30, 2019 and 2018.
Business Consolidation Costs and Other Activities
Business consolidation and other activities were zero and $14 million for the three and six months ended June 30, 2019, respectively, and $69 million and $99 million for the three and six months ended June 30, 2018. These amounts represented less than one percent of consolidated net sales for the six months ended June 30, 2019, and 2 percent for the three and six months ended June 30, 2018. The decrease for the three and six months ended June 30, 2019, was primarily due to a gain on indirect taxes in Brazil and lower facility shut down and consolidation costs.
Interest Expense
Total interest expense was $81 million and $162 million for the three and six months ended June 30, 2019, respectively, compared to $77 million and $151 million for the same periods in 2018. Interest expense as a percentage of average monthly borrowings was 4 percent for the three and six months ended June 30 2019 and 2018.