Earnings improved substantially but earnings per share of $0.73, compared to $0.48 in the pandemic impacted first quarter of last year.
First quarter revenue was $670 million, a decrease of $30 million, compared to the same quarter last year.
Our same-store revenue declined by $83 million.
However, our recent acquisitions added approximately $53 million in revenue this quarter.
Gross profit was $123 million for the first quarter of 2021, an increase of $6 million and gross profit as a percentage of revenue rose to 18.4% in the first quarter of 2021, compared to 16.7% for the first quarter of 2020.
SG&A expense was $88 million, or 13.2% of revenue for the first quarter of 2021, compared to $93 million, or 13.3% of revenue for the first quarter of 2020.
On a same-store basis, SG&A declined by $6 million -- $11 million.
That decrease included a $6 million reduction in bad debt expense as last year's collectability concerns for retail and other customers are trending better than we predicted.
Our 2021 tax rate was 24.8%, compared to 27.6% in 2020.
Overall net income for the first quarter of 2021 was $26 million, or $0.73 per share, as compared to $18 million, or $0.48 per share in 2020.
For our first quarter, EBITDA was $51 million, a 39% improvement over last year and our trailing 12-month EBITDA is a record $264 million.
Free cash flow in the first quarter was $80 million, as compared to $15 million in Q1 2020.
Our free cash flow over the trailing 12-month period is $330 million and that strong performance has returned our leverage to well under 1 times EBITDA despite our many ongoing and recent acquisitions.
Backlog at the end of the first quarter of 2021 was $1.66 billion.
We believe that the effects of the pandemic are beginning to subside as same-store backlog increased sequentially by nearly $150 million, or 10%.
Our industrial revenue was 40% of total revenue in the first quarter.
Institutional markets, which include education, healthcare and government were 35% of our revenue and that is roughly consistent with what we saw in 2020.
The commercial sector is now about 25% of our revenue.
For the first quarter of 2021, construction was 77% of our revenue, with 45% from construction projects for new buildings and 32% from construction projects in existing buildings.
Service was 23% of our first quarter 2021 revenue with service projects providing 9% of revenue, and pure service, including hourly work providing 14% of revenue.
Year-over-year service revenue is up approximately 4% with improved profitability.
Our electrical gross margins improved from 5.5% in the first quarter of 2020 to 14.7% this year.

Summary:
Earnings improved substantially but earnings per share of $0.73, compared to $0.48 in the pandemic impacted first quarter of last year.
Overall net income for the first quarter of 2021 was $26 million, or $0.73 per share, as compared to $18 million, or $0.48 per share in 2020.
Backlog at the end of the first quarter of 2021 was $1.66 billion.