The safety of our employees remains our number 1 priority.
Sales in the quarter were $1.2 billion, down 8% compared to the fourth quarter of 2019.
Organic sales were also down 8% with the divestiture of Reading Alloys, a three point headwind, the acquisition of IntelliPower contributing one point to growth and foreign currency added two points.
As we saw in prior quarters, our commercial aerospace business was the most impacted by the pandemic with sales down approximately 35% in the quarter.
Orders continued to improve with our book-to-bill at 1.07 for the fourth quarter.
This led to a record backlog of $1.8 billion, providing us with a positive line of sight into 2021.
Operating income in the fourth quarter was $298.1 million, up slightly from the fourth quarter of 2020, and operating margins were a record 24.9%, up an impressive 210 basis points compared to the prior year period.
EBITDA in the fourth quarter was a record $360.7 million and EBITDA margins were also a record of 30.1%, up a robust 300 basis points over the fourth quarter of 2019.
This operating performance led to earnings per diluted share of $1.08, matching last year's fourth quarter results and comfortably ahead of our guidance for the quarter.
With operating cash flow up 13% to a record $386 million and free cash flow conversion, exceptional 158% of net income.
EIG sales in the fourth quarter were $819.4 million, down 7% from the prior year and in line with our expectations of solid sequential improvement.
Organic sales were down 10%, with the acquisition of IntelliPower contributing 2%, and foreign currency contributing 1%.
Despite the overall sales decline, EIG's operating income in the fourth quarter increased 3% over the prior year to a record $236 million, and operating margins reached a new high of 28.8%, expanding an exceptional 270 basis points over the same period in 2019.
EMG sales were $379.5 million, down 11% from the fourth quarter in 2019, driven in large part by the divestiture of Reading Alloys.
Organic sales were down 4%, with the divestiture an 8-point headwind, and foreign currency adding two points.
Fourth quarter operating income for EMG was $79.8 million, and operating margin expanded an impressive 110 basis points to 21%.
Overall sales for the year were $4.5 billion, down 12% from 2019.
Organic sales declined 13%, with acquisitions adding 4%, the divestiture of Reading Alloys a 3% headwind, and foreign currency flat for the year.
Operating income in 2020 was $1.1 billion and operating margins were a record 23.6%, expanding 80 basis points over 2019.
EBITDA for the year was $1.32 billion and EBITDA margins were a record 29.2%, up 230 basis points from last year.
This led to full year earnings of $3.95 per diluted share, down 6% versus the prior year.
As Bill will highlight, our businesses did a fantastic job managing our working capital, which helped drive a record level of cash flow with full year operating cash flow up 15% to $1.28 billion.
In the fourth quarter, we generated $60 million in total cost savings with $50 million of structural savings and $10 million in temporary savings.
And for the full year, total incremental savings versus the prior year were $235 million, with approximately $145 million of structural savings and $90 million in temporary savings, including furloughs, travel reductions and temporary pay actions.
For the full year 2021, we expect approximately $140 million of incremental operational excellence savings.
In 2020, we invested $246 million in research, development and engineering, approximately 5.5% of sales.
In the fourth quarter, our vitality index or the percent of sales generated from products introduced over the last three years was an impressive 25%.
In 2021, we expect to invest approximately $270 million or 5.5% of sales in research, development and engineering to enhance our position as a global technology leader.
This is a 10% increase over 2020 RD&E spend.
As Bill will discuss shortly, AMETEK has significant balance sheet capacity and, when combined with our robust cash flow generation, provides us with meaningful capital to support our acquisition strategy, which remains our number 1 priority for capital development -- deployment.
For the year, we expect both overall and organic sales to be up mid-single digits versus 2020.
Diluted earnings per share for the year are expected to be in the range of $4.18 to $4.30, up 6% to 9% compared to 2020.
For the first quarter, we anticipate continued year-over-year impact from the pandemic, with overall sales down low to mid-single digits and first quarter earnings of $0.97 to $1.02 per share, flat to down 5% versus the prior year.
Fourth quarter general and administrative expenses were $17.7 million, up modestly from the prior year.
For the full year, G&A was down 11% from 2019 due to lower compensation costs and other discretionary cost reductions and, as a percentage of total sales, was 1.5% in both years.
For 2021, general and administrative expenses are expected to be up approximately 10% due primarily to the return of temporary costs, including compensation.
The effective tax rate in the fourth quarter was 20.1%, up from 17.6% in the fourth quarter of 2019.
For 2021, assuming the current tax regime, we anticipate our effective tax rate to be between 19% and 20%.
Operating working capital was an impressive 14% in the fourth quarter, down 330 basis points from the 17.3% reported in the same quarter last year, reflecting the outstanding work by our teams.
Capital expenditures were $37 million in the fourth quarter and $74 million for the full year.
Capital expenditures in 2021 are expected to be approximately $110 million.
Depreciation and amortization in the quarter was $65 million and for the full year was $255 million.
In 2021, we expect depreciation and amortization to be approximately $260 million, including after-tax, acquisition-related intangible amortization of approximately $117 million or $0.50 per diluted share.
Operating cash flow in the quarter was a record $386 million, up 13% over last year's fourth quarter.
Free cash flow was also a record at $349 million, up 16% over the same period last year, resulting in a free cash flow conversion of 158% of net income.
Operating cash flow for 2020 was $1.28 billion, up 15% over the prior year, and free cash flow was $1.21 billion, a year-over-year increase of 19%.
Full year free cash flow conversion was 158% of net income adjusted for the Reading Alloys gain.
Total debt at December 31 was $2.41 billion, down from $2.77 billion at the end of 2019.
Offsetting this debt is cash and cash equivalents of $1.2 billion.
Our gross debt-to-EBITDA ratio was 1.8 times and our net debt-to-EBITDA ratio was 0.9 times at year-end.
We entered 2021 with approximately $2.6 billion in liquidity to support our growth initiatives.

Summary:
Sales in the quarter were $1.2 billion, down 8% compared to the fourth quarter of 2019.
This operating performance led to earnings per diluted share of $1.08, matching last year's fourth quarter results and comfortably ahead of our guidance for the quarter.
For the year, we expect both overall and organic sales to be up mid-single digits versus 2020.
Diluted earnings per share for the year are expected to be in the range of $4.18 to $4.30, up 6% to 9% compared to 2020.
For the first quarter, we anticipate continued year-over-year impact from the pandemic, with overall sales down low to mid-single digits and first quarter earnings of $0.97 to $1.02 per share, flat to down 5% versus the prior year.
Offsetting this debt is cash and cash equivalents of $1.2 billion.