Growth continued in the first quarter of 2021, with net organic sales increasing 2% year-over-year.
Notably, this follows a very strong first quarter of 2020, where net organic sales growth was 7%.
Over the last 12 months, we've exceeded our targets, delivering 3% net organic sales growth.
Importantly, we continue to have confidence in our 100 to 200 basis points goal for annual net organic sales growth established with Vision 2025.
As we look out specifically at the year to the anticipated volume from our innovation pipeline, coupled with return to growth in foodservice, we expect 2021 net organic sales growth will be at the high end of our 100 to 200 basis point range.
Adjusted EBITDA in the quarter of $240 million met our expectations before the $29 million of costs we incurred associated with winter storm Uri.
Also during the quarter, we made further progress on the Vision 2025 goal of achieving 80% to 90% paperboard integration across our consolidated business.
We exited the first quarter of 2021 at 71%, improving from 70% in the full year of 2020 and 68% in 2019.
Our partnership with International Paper continue to wind down during the quarter as we acquired another $400 million of minority partnership interest, reducing their interest to 7% from the initial 21% held at the inception of the partnership.
We have entered into an agreement to acquire Americraft Carton for approximately $280 million.
The company is one of the largest remaining independent converters in North America, with over $200 million in annual sales, operating seven well-capitalized and high-quality converting facilities.
The company has a great reputation with customers, has been in business for over 100 years and generates approximately $30 million of annual EBITDA.
We see 300 basis points of paperboard integration opportunity across all three substrates and expect an additional $10 million of synergies over 24 months following the close.
With the launch of the PaperSeal in 2020, we targeted a $1 billion addressable market opportunity to replace foam trays and shrink wrap alternatives commonly found in the grocery store meat departments around the world.
Providing packaging enhancements for consumers that include 100% recyclability and reduced carbon footprint will be the key to our new product development road map moving forward.
We are confident in the pipeline in front of us to achieve a 100 to 200 basis of annual net organic sales growth and expect to be at the high end of that range in 2021.
Net sales increased 3% from the prior year to $1.65 billion, driven by 2% net organic sales growth and positions.
Adjusted EBITDA declined from the prior year quarter, primarily related to $29 million in costs associated with winter storm Uri and maintenance downtime.
As a result, adjusted earnings per share were $0.23 as compared to $0.31 in the first quarter of 2020.
Total liquidity remained significant at $1.44 billion.
Solid sales performance was driven by continued strength food, beverage and consumer markets, where sales before acquisitions increased 5%.
Partially offsetting this performance was our foodservice business, where sales declined 10% versus the prior year period.
On Slides 11 and 12, you'll see our year-over-year revenue and EBITDA waterfall.
Net sales increased $50 million in the first quarter of 2021, driven by $33 million of improved volume mix, resulting from a combination of 2% organic sales growth and acquisitions, partially offset by fewer selling days when compared to leap year observed in the prior year quarter as well as $20 million of favorable foreign exchange.
Adjusted EBITDA decreased $55 million to $240 million in the first quarter of 2021.
Adjusted EBITDA benefited from $21 million in improved net productivity and $5 million from favorable foreign exchange.
EBITDA was unfavorably impacted by $3 million of pricing, $2 million of unfavorable volume mix, $34 million of commodity input cost inflation, $13 million of other inflation and $29 million of costs related to winter storm Uri.
Excluding storm-related costs, adjusted EBITDA was $269 million, consistent with our expectations.
AF&PA industry operating rates at the end of Q1 for SBS and CRB were 92% and 94%, respectively.
Our CUK operating rate was over 95%, as we remained in an oversubscribed environment.
We ended the quarter with net leverage at 3.7 times.
While leverage is above our long-term targeted level of 2.5 times to three times and our 2021 target of three times to 3.5 times, we remain confident in our cash flow generation commitments and increase in expected cash flow generation in 2022.
We issued $800 million in two senior secured notes offerings.
What is notable about these transactions are the annual interest rates of the 2024 notes at 0.8% and the 2026 notes at 1.5%.
We also retired $425 million of maturing higher interest rate bonds, with an attractive farm credit system loan.
And earlier this month, we completed an amend and extend to our bank credit facility, which notably extended the maturity date from January 2023 to April 2026 and increased the availability under the domestic revolving line of credit by $400 million.
Turning now to guidance on Slides 13 and 14.
As Mike mentioned, we expect 2021 net organic sales growth to be at the high end of our 100 to 200 basis points target range.
While some components of adjusted EBITDA have changed given the operating environment we are managing, our full year adjusted EBITDA guidance range of $1.09 billion to $1.15 billion provided at the beginning of 2021 remains unchanged due to the numerous pricing, volume and productivity initiatives we are committed to successfully executing throughout the remainder of the year.

Summary:
We have entered into an agreement to acquire Americraft Carton for approximately $280 million.
The company is one of the largest remaining independent converters in North America, with over $200 million in annual sales, operating seven well-capitalized and high-quality converting facilities.
Net sales increased 3% from the prior year to $1.65 billion, driven by 2% net organic sales growth and positions.
As a result, adjusted earnings per share were $0.23 as compared to $0.31 in the first quarter of 2020.
As Mike mentioned, we expect 2021 net organic sales growth to be at the high end of our 100 to 200 basis points target range.