Net sales of $798.4 million increased $115 million or 16.8% compared to last year, due to significantly higher sales in the Irrigation and Utility Support Structures segments.
Starting with Utility, sales of $271 million, grew 16.9% year-over-year, led by significantly higher sales of global generation products, as expected.
Moving to Engineered Support Structures, sales of $256.1 million were similar to last year.
Turning to Coatings, sales of $89.3 million, were similar to last year, but improved sequentially from the third quarter as demand continues to recover.
In Irrigation, sales of $199.3 million, grew nearly 50% compared to last year with growth across all global regions.
During the quarter, we purchased the remaining 40% stake of Torrent Engineering and Equipment, a global designer integrator of high pressure water systems for the agricultural and industrial sectors.
Turning to the full year summary on slide 5, net sales of $2.9 billion, grew 4.6% compared to last year and 5.4 % excluding currency impacts.
Access Systems sales were down 23% compared to last year due to a strategic decision to exit certain product lines.
Turning to Coatings, sales were down 6.1% for the year, but improved sequentially in the second half of the year, tracking in line with improving industrial production levels.
In Brazil, very strong demand led to record sales with sales in local currency, growing 32% year-over-year.
Additionally, sales of advanced technology solutions globally grew nearly 20% year-over-year to $67 million.
These proprietary solutions now connect over 110,000 of our growers machines helping them to maximize yields, improve water efficiency and optimize input costs.
We accelerated innovation through new products and services including our Spun Concrete Distribution Poles and small cell solutions, as well as technology advancements in our Valley 365 platform for connected crop management and all segments benefited from disciplined pricing strategies throughout the year.
We secured the largest irrigation order in the industry's history to supply $240 million of products, services and technology solutions to the Egypt market and we generated over $200 million in free cash flow through a continued intense focus on working capital management.
Together, we have committed to build a local facility with an annual production capacity of up to 1000 pivots.
As the largest economy in the region, Kazakhstan is rapidly embracing agriculture as a key economic contributor with a national plan to more than double the number of irrigated acres over the next 10 years.
Growing regional demand coupled with excellent infrastructure will allow us to quickly and efficiently serve the greater market, starting with the multi-year agreement to supply a minimum of 4000 pivots.
Fourth quarter operating income of $68.8 million or 8.6% of sales, grew 180 basis points, or 36% compared to last year, driven by improved operational efficiency in all segments, higher volumes in Utility and Irrigation and the non-recurrence of last year's losses in the Access System product line.
Fourth quarter diluted earnings per share of $2.20, grew 46% compared to last year, driven by higher net earnings and non-recurrence of losses in the Access Systems business and a more favorable tax rate.
Fourth quarter tax rate was 24.4% on an adjusted basis.
This excludes a non-recurring $1 million benefit or $0.05 per share from the adoption of US Tax Regulation finalized in 2020 which allows for more favorable treatment of tax payments by our foreign subsidiaries.
Turning to the Segments, on slide 10, in Utility Support Structures operating income of $28 million or 10.3% of sales decreased 110 basis points compared to last year.
Moving to slide 11, in Engineered Support Structures, operating income of $24.4 million or 9.5% of sales increased 540 basis points over the last year.
Turning to slide 12, in the Coatings Segment, operating income of $11.8 million or 13.2% of sales was similar to last year.
Moving to slide 13, in the Irrigation Segment, operating income of $25.3 million or 12.7% of sales, was 380 basis points higher, compared to last year.
Turning to cash flow on slide 14, our rigorous focus on working capital management helped us deliver solid operating cash flow of $316.3 million this year, an improvement over last year's strong performance and despite an early payment of approximately $18 million for the required 2021 Annual UK Pension Plan contribution.
Capital spending for 2020 was $107 million, which includes approximately $42 million of investment in strategic growth opportunities and approximately $60 million of maintenance capital in line with historical levels.
As mentioned last quarter, we resumed our share repurchase program in September returning approximately $93.4 million of capital to shareholders through dividends and share repurchases in 2020, ending the year with approximately $400 million of cash.
Our balance sheet remains strong with no significant long-term debt maturities until 2044.
Our leverage ratio of total debt to adjusted EBITDA of 2.2 times remains within our desired range of 1.5 to 2.5 times and our net debt to adjusted EBITDA is at one time.
For the first quarter, we estimate net sales to be between $740 million and $765 million and operating income margins between 9% to 10% of net sales.
For the full year, net sales are estimated to increase 9% to 14% year-over-year, which assumes a foreign currency translation benefit of 2% of net sales.
Earnings per share is estimated to be between $9 and $9.70, excluding any restructuring activities.
A reminder that pricing actions in response to rapid inflation in this segment historically take one to two quarters to recover, so we expect unfavorable gross margin comparisons of approximately 220 basis points in the first half of the year when compared to 2020.
Moving to Engineered Support Structures, we have entered the year with a solid global backlog of $247 million.
We expect demand for wireless communication products and components remains strong and anticipate curious investment in 5G to accelerate throughout 2021, with sales expected to grow approximately 15% this year.
Full year sales are expected to substantially increase 27% to 30% year-over-year.
Finally, as part of our ongoing strategic portfolio review, we have decided to divest the access System product line, which generated $88 million of sales in 2020 and serves the Australia and Asia-Pacific markets.
Moving to slide 19, as we have consistently stated over the past year, the fundamental market drivers of our business remain intact and we are seeing a solid set up for 2021 across all end markets as evidenced by our record, $1.1 billion backlog at the end of the year.
In Utility, our strong year-end backlog of nearly $565 million remains at elevated levels and demonstrates the ongoing demand and necessity for renewable energy solutions and grid hardening.
We are pleased to announce that in the first quarter, we were awarded the third purchase order of approximately $70 million for the large project in the Southeast U.S., confirming our customers' confidence in our execution, quality and value.
If one is past, this segment will experience upside growth approximately 9 to 12 months after an enactment.
And in Irrigation, recent improvements in net farm income have improve grower sentiment and tighter ending stocks have driven corn and soybean prices to 6 and 7 year highs.
This improved demand along with strength across international markets and the large-scale multi-year project in Egypt is providing a good line of sight for 2021 as evidenced by our year-end global backlog of $328 million, an increase of 5 times the level from one year ago.
As we entered the third year of offering this innovative solution, I'm excited to share that the number of monitored acres more than doubled to $5 million in 2020 leading to twice as many growers using the service as compared to 2019.
Altogether, I am very proud that approximately 90% of Valmonts net sales supports ESG efforts.
As the world continues to transition to a clean energy economy, approximately 90% of our Utility Support Structures sales are tied to ESG, including 45% to renewable energy initiatives and 45% to grid resiliency and critical reliability efforts.
Approximately 90% of Engineered Support Structures sales are also attributable to ESG.
In coatings, nearly 100% of our sales helps preserve and extend the life of metals up to 3 times longer.
Zinc and steel are both 100% recyclable and hot-dip galvanizing is a proven corrosion protection system and has one of the lowest carbon footprints of any coatings application.
In terms of our own sustainability efforts, I'm very pleased that at the end of 2020, we exceeded our global electricity conservation goal set in 2018, resulting in a 14% reduction in normalized electricity consumption, well ahead of our 8% goal.
As a further benefit, we also reduced our scope to carbon footprint by approximately 10,000 metric tons in 2020, a notable accomplishment by our green teams.
As we prepare to celebrate our 75th anniversary as a company in March, I want to again recognize our 10,000 global employees.

Summary:
Net sales of $798.4 million increased $115 million or 16.8% compared to last year, due to significantly higher sales in the Irrigation and Utility Support Structures segments.
Fourth quarter diluted earnings per share of $2.20, grew 46% compared to last year, driven by higher net earnings and non-recurrence of losses in the Access Systems business and a more favorable tax rate.
For the first quarter, we estimate net sales to be between $740 million and $765 million and operating income margins between 9% to 10% of net sales.
Earnings per share is estimated to be between $9 and $9.70, excluding any restructuring activities.