During the three months ended June 30, 2021, cost of sales increased to $12,955,028, or 106% of sales, compared to $8,488,095, or 113% of sales for the 2020 period. Cost of sales includes non-cash depreciation expense of $1,319,104 for the three months ended June 30, 2021, and $1,429,692 for the comparable period in 2020. The cost of sales exceeding revenues during 2021 and 2020 was the result of lower than required revenues to cover fixed costs within cost of sales.
Selling, general and administrative expenses for the three months ended June 30, 2021 was $1,617,201, or 13.2% of revenues, compared to $941,574, or 12.6% of revenues, for the quarter ended June 30, 2020. The increased dollar amount and percent of revenue are primarily driven by improved revenue.
Interest expense was $1,321,988 and $1,131,472 for the three months ended June 30, 2021 and 2020, respectively.
The net loss from continuing operations for the quarter ended June 30, 2021 was $419,360 as compared to a net loss of $2,976,940 for the quarter ended June 30, 2020. The reduction in the net loss was due primarily to the Gain on PPP loan forgiveness of $3,148,100 recorded as Other Income.
Six Months Ended June 30, 2021 Compared to the Six Months Ended June 30, 2020
Revenues for the six months ended June 30, 2021 increased to $19,845,419 from $11,859,607 for the six months ended June 30, 2020, driven by the acquisition of 5J on February 27, 2020, increased drilling rig relocations, improved customer demand resulting from lessened impacts of the global COVID-19 pandemic and to the establishment of a new Houston terminal.
During the six months ended June 30, 2021, cost of sales increased was $21,655,536 or 109% of sales, compared to $13,151,454 or 111% of sales for the 2020 period. Cost of sales includes non-cash depreciation expense of $2,737,505 for the six months June 30, 2021, and $1,972,185 for the comparable period in 2020, the increase in which was driven primarily by the 5J acquisition and the related fair value step up adjustments in the prior year. The cost of sales exceeding revenues during 2021 and 2020 was the result of lower than required revenues to cover fixed costs within cost of sales.
Selling, general and administrative expenses for the six months ended June 30, 2021 was $3,129,601 or 15.8% of revenues, compared to $3,039,904, which included $1,489,417 of 5J acquisition costs. Excluding these costs, selling, general and administrative costs for the six months ended June 30, 2020 were $1,550,487, or 13.0% of revenues.
Interest expense was $2,570,777 and $1,476,071 for the six months ended June 30, 2021 and 2020, respectively. The increase is a result of the borrowings to fund the 5J acquisition.
The net loss from continuing operations for the six months ended June 30, 2021 was $4,277,928 as compared to a net loss of $5,722,847 for the six months ended June 30, 2020. The reduction in the net loss was due primarily to the Gain on PPP loan forgiveness of $3,148,100 recorded as Other Income.
We plan to address our net loss and future operating results with a goal to achieve positive cash flow from operations by increasing sales organically or through acquisitions, covering more fixed costs within cost of sales, improving gross margins with better sales mix adding more higher margin service revenues such as super heavy haul, and reducing general and administrative costs including professional fees.
Liquidity and Capital Resources
Cash Flows
Operating activities
Net cash used in operating activities was $4,170,176 for the quarter ended June 30, 2021, compared to $2,219,563 for the quarter ended June 30, 2020, including $608,519 of cash provided by discontinued operations during the quarter ended June 30, 2021, and $581,439 of cash used in discontinued operations during the quarter ended June 30, 2020.