These top line improvements, along with our steadfast focus on cost controls, resulted in 7% growth in consolidated total revenues; 20% growth in adjusted earnings before interest, taxes, depreciation and amortization or adjusted EBITDA; and a 40% increase in diluted earnings per share.
Specifically, full year consolidated products and services revenues increased to $4.4 billion.
Consolidated gross profit increased 6% to $1.3 billion.
Adjusted EBITDA increased 11% to nearly $1.4 billion, and diluted earnings per share was $11.54, an 18% improvement.
We achieved a 25% reduction in total reportable incidents across the enterprise in 2020, and for the fourth consecutive year, we achieved a companywide world-class lost time incident rate.
These superior financial and safety results are directly attributable to the dedication and agility of our nearly 9,000 talented employees.
Aggregate shipments declined 2% to nearly 187 million tons, reflecting anticipated lower infrastructure shipments in portions of North Carolina, reduced energy sector demand and headwinds from COVID-19 disruptions.
Aggregates average selling price increased 4% on a mix adjusted basis, in line with our expectations.
Our cement operations established new records for shipments, which increased 2% to nearly four million tons.
Pricing increased 3% on a mix adjusted basis, demonstrating the resilient price fundamentals of core products in the state of Texas.
Ready mixed concrete shipments increased 3%, excluding shipments from acquired operations and from our Southwest division's former concrete business in Arkansas, Louisiana and Eastern Texas, which we divested in January 2020.
Concrete pricing increased 2%.
Our Colorado asphalt and paving business established a new record for asphalt shipments, increasing 15% to three million tons.
Asphalt pricing increased nearly 3%.
Driving this achievement was our Building Materials business, which delivered record products and services revenues of $4.2 billion, a 1% increase, and record product gross profit of $1.2 billion, a 7% increase.
Aggregates product gross margin expanded 130 basis points to 30.6%, a new record, and unit profitability improved 8%.
We achieved 90% kiln reliability this year, up from 82% in 2019, which facilitated increased throughput and fixed cost absorption at both our Midlothian and Hunter plants.
These factors, combined with mix adjusted pricing strength and lower fuel costs contributed to the 510 basis point improvement in cement product gross margin to 37.8%.
Ready mixed concrete product gross margin increased 10 basis points to 8.4% as pricing growth offset higher raw material costs.
Asphalt and paving achieved gross profit of $60 million and a 100 basis point improvement in gross margin, driven by double-digit revenue growth.
The 12% top line improvement in the quarter, however, was not enough to offset demand declines experienced earlier in the year.
As a result, full year product revenues decreased 12% to $221 million.
Impressively, product gross margin improved 80 basis points to 40.6% as we proactively responded to lower shipments with effective cost control measures.
Operating cash flow of $1.05 billion increased 9%, driven by earnings growth.
For 2020, we invested $360 million of capital into our business and returned $190 million to shareholders through both an increased dividend and the first quarter repurchase of 211,000 shares of our common stock.
In August 2020, our Board approved a 4% increase in our quarterly cash dividend, underscoring its continued confidence in our future performance and continuing Martin Marietta's track record of dividend growth.
Since our repurchase authorization announcement in February 2015, we have returned more than $1.8 billion to shareholders through a combination of meaningful and sustainable dividends as well as share repurchases.
We ended 2020 with a debt-to-EBITDA ratio of 1.9 times, slightly below our target leverage range of two to 2.5 times, which offers us the flexibility to pursue accretive investment opportunities.
Our solid balance sheet, combined with $1.1 billion of availability on our credit facilities, provides the financial strength for Martin Marietta to respond to, then execute on disciplined capital allocation priorities and continue profitably growing our business.
Keep in mind, our top five states: Texas, Colorado, North Carolina, Georgia and Florida, are disproportionately important to us, representing 71% of our 2020 Building Materials business total revenues.
Additionally, DOTs were recently granted nearly $10 billion of targeted relief as part of the Coronavirus Response and Relief Act passed in December 2020 to help offset pandemic-driven transportation revenue shortfalls.
Based on preliminary estimates, over $2 billion of this assistance will be apportioned to Martin Marietta's top five states.
In November 2020, voters sent a powerful message of support for state and local transportation investment, approving 94% of ballot measures, the highest ever approval rating.
These initiatives are estimated to generate an additional $14 billion in onetime and recurring transportation funding, of which 82% is in Texas, our top revenue-generating state.
Bipartisan support exists for new surface transportation legislation aimed at increasing funding levels not seen in over 15 years, with both the United States House of Representatives and Senate previously advancing proposed bills.
We expect increased infrastructure investment to provide volume stability and drive aggregate shipments in that end-use closer to our 10-year historical average of 43% of our total shipments.
For reference, aggregate shipments to the infrastructure market accounted for 36% of 2020 shipments.
Aggregate shipments to the nonresidential market accounted for 34% of 2020 shipments.
Aggregates to the residential market accounted for 24% of 2020 shipments.
We currently expect 2021 aggregates shipment growth to range from up 1% to up 4%, reflecting single-family housing strength, expanded infrastructure investment and heavy industrial projects of scale that will support our near-term shipment levels.
For 2021, we expect annual aggregates price increases, which become effective from January one to April 1, to increase in a range of up 3% to up 5%.
Combined with contributions from our Cement, Downstream and Magnesia Specialties businesses, on a consolidated basis, we expect adjusted EBITDA of $1.350 billion to $1.450 billion.
To conclude, we're proud of our 2020 record financial results and industry-leading safety performance.

Summary:
Consolidated gross profit increased 6% to $1.3 billion.
To conclude, we're proud of our 2020 record financial results and industry-leading safety performance.