Overall, our performance in the fourth quarter represented a strong finish to 2020, a year in which we delivered the second highest adjusted earnings per share in the company's history, surpassed only by the $1.79 per share reported in 2019.
The despite the impact of the pandemic on our top line, I was pleased with how our teams responded quickly, taking actions to control costs, which not only preserved our EBITDA margin but improved it by 40 basis points on a year-over-year basis.
Second, we continue to invest in new product development, and we are seeing the benefits from these efforts with an estimated $200 million of revenue in 2020 being generated from the sales of products introduced in the last three years.
Among those products was the 2100 I full-size tower cleaner, which we launched in 2018.
The 2100 I sewer cleaner introduced intelligent controls on the truck and was entirely designed around our customers' needs for ease of use and operability.
During 2020 and on the back of our success with the 2100 I, we launched a smaller sewer cleaner and a truck jetter machine that incorporates the same intelligent controls as the 2100 I. The initial response to these products has been very positive.
Overall, revenues from these new products accounted for nearly 10% of TBIS overall revenues during a year in which TBI delivered the highest EBITDA margin under our ownership.
Of our total R&D spend in 2020, approximately 20% was invested in electrification projects, and we are pleased to report that during the fourth quarter, we received our first orders for our hybrid electric street sleeper.
Although we expect this acquisition to be neutral to our 2021 earnings, the acquisition provides considerable opportunity for long-term value creation through the application of our 80/20 improvement principles, organic growth initiatives and additional bolt-on acquisitions.
Consolidated net sales for the year were approximately $1.13 billion, down about 7% compared to the prior year.
Operating income for the year was $131.4 million compared to $147.1 million in the prior year.
Consolidated adjusted EBITDA for the year was $182.2 million compared to $191.3 million in the prior year.
That translates to a margin of 16.1% for the year, up 40 basis points from the prior year and above the high end of our target range.
GAAP earnings for the year equated to $1.56 per share compared to $1.76 per share in 2019.
On an adjusted basis, we reported full year earnings of $1.67 per share compared to $1.79 per share in the prior year.
Consolidated net sales for the quarter were $295 million compared to $314 million in the prior year.
Consolidated operating income for the quarter was $33.8 million compared to $36.4 million in the prior year.
On an adjusted basis, consolidated operating margin was 12%, up 10 basis points from the prior year.
Consolidated adjusted EBITDA for the quarter was $47 million compared to $48.5 million in the prior year.
That translates to a margin of 15.9% for the quarter, an improvement of 50 basis points over the prior year.
Income from continuing operations for the quarter was $26 million compared to $29.7 million in the prior year.
That equates to GAAP earnings per share of $0.42 per share for the quarter compared to $0.48 per share in the prior year.
On an adjusted basis, earnings per share for the quarter was $0.44 per share, which compares to $0.48 per share in the prior year.
Orders for the quarter were $276 million, down from record levels in the prior year quarter, but up $10 million or 4% from the third quarter of 2020.
That momentum continued into 2021, with strong order intake in January, contributing to a backlog of $330 million at the end of last month.
That represents an increase from $304 million at the end of 2020.
In terms of our fourth quarter group results, ESG sales were $238 million compared to $252 million in the prior year.
ESG's adjusted EBITDA for the quarter was $44.2 million, up 1% from the prior year.
That translates to an adjusted EBITDA margin for the quarter of 18.6%, above our target range and up 120 basis points from the prior year.
Our aftermarket revenues for the quarter were up about 11% year-over-year, again contributing to the strong margin performance.
Overall, our aftermarket revenues represented roughly 25% of ESG's revenues for the quarter, which is up from 21% in the prior year period.
SSG sales for the quarter were $57 million compared to $62 million in the prior year.
SSG's adjusted EBITDA for the quarter was $11.2 million compared to $12.6 million in the prior year, and its adjusted EBITDA margin for the quarter was 19.6% compared to 20.3% in the prior year.
Corporate operating expenses for the quarter were $9.8 million compared to $8.4 million in the prior year with the increase primarily related to unfavorable fair value adjustments of certain post-retirement reserves, which represented a headwind of about $0.02 in the quarter and higher M&A expenses.
Turning now to the consolidated income statement, where the decrease in sales contributed to a $5.6 million reduction in gross profit.
Consolidated gross margin for the quarter was 25.7% compared to 25.9% in the prior year.
As a percentage of sales, our selling, engineering, general and administrative expenses for the quarter were down 40 basis points from the prior year.
Other items affecting the quarterly results include a $700,000 increase in acquisition-related expenses, a $1.1 million increase in other income and a $600,000 reduction in interest expense.
Compared to the prior year, tax expense for the quarter increased by $2.8 million, largely due to the recognition of fewer discrete tax benefits than in the prior year quarter.
Although it was up on a year-over-year basis, our effective tax rate for the quarter was lower than we expected at around 23%, primarily due to the recognition of benefits associated with stock compensation activity and other discrete items, which collectively added about $0.03 to our fourth quarter EPS.
For 2021, we currently expect a tax rate of approximately 24%.
On an overall GAAP basis, we, therefore, earned $0.42 per share in the quarter compared with $0.48 per share in the prior year.
On this basis, our adjusted earnings for the quarter were $0.44 per share compared with $0.48 per share in the prior year.
Looking now at cash flow, where we generated $57 million of cash from operations in the quarter, bringing the total amount of operating cash generation for the year to $136 million.
That represents a year-over-year improvement of $33 million or 32%.
The improved cash flow facilitated a $30 million debt reduction in the quarter as well as continued strategic investments in new machinery and equipment and other organic growth initiatives like the expansion of several of our manufacturing facilities.
In 2021, we are currently anticipating that our capex, including investments associated with ongoing plant expansions will be lower than in 2020 and in the range of between $20 million and $25 million.
We ended the year with $128 million of net debt and availability of $280 million under our credit facility.
As a reminder, we executed a new five year $500 million credit facility in July of 2019.
We also have the option to trigger an increase in our borrowing capacity by an additional $250 million for acquisitions.
On that note, we paid a dividend of $0.08 per share during the fourth quarter, amounting to $4.9 million, and we recently announced that we are increasing the dividend by 13% to $0.09 per share in the first quarter.
Our aftermarket business has grown to represent about 1/4 of ESG's revenues, and we see additional opportunities to grow that business.
We have also worked to develop strong contingency planning protocols, continue our journey of 80/20 and invest for growth.
The initial proposal under the American Rescue Plan, COVID relief package call for approximately $1.9 trillion of economic stimulus with initial projections of approximately $350 billion going to state, local and territorial governments with the goal of keeping frontline workers employed, distributing the vaccine, increasing testing, reopening schools and maintaining essential services.
An estimated 47,000 bridges and 40% of our highways are in need of replacement, whereas entire sewer systems have exceeded their useful life cycles.
On the flip side, we are anticipating that some of the cost savings that resulted from actions taken in 2020 are expected to return in 2021, representing an estimated year-over-year expense headwind of approximately $8 million.
In the first quarter of 2020, we also recognized a benefit of approximately $0.02 per share associated with fair value adjustments to certain reserves.
Yet despite this, we are expecting a strong year in 2021 with top line growth, double-digit improvement in pre-tax earnings and adjusted earnings per share of between $1.73 and $1.85.

Summary:
Consolidated net sales for the quarter were $295 million compared to $314 million in the prior year.
That equates to GAAP earnings per share of $0.42 per share for the quarter compared to $0.48 per share in the prior year.
On an adjusted basis, earnings per share for the quarter was $0.44 per share, which compares to $0.48 per share in the prior year.
On an overall GAAP basis, we, therefore, earned $0.42 per share in the quarter compared with $0.48 per share in the prior year.
On this basis, our adjusted earnings for the quarter were $0.44 per share compared with $0.48 per share in the prior year.
Yet despite this, we are expecting a strong year in 2021 with top line growth, double-digit improvement in pre-tax earnings and adjusted earnings per share of between $1.73 and $1.85.