months ended June 30, 2019, we had four commercial and rural real estate sales totaling approximately 34 acres for $1.3 million, resulting in a gross profit margin of approximately 92.3%.
Timber revenue increased by $1.3 million during the three months ended June 30, 2020, as compared to the same period in 2019. The increase is primarily due to an increase in the amount of tons sold and product mix changes. The revenue for the three months ended June 30, 2019, was affected by Hurricane Michael’s significant market impact after landfall in October 2018. There were 105,000 tons sold during the three months ended June 30, 2020, as compared to 31,000 tons sold during the same period in 2019. The average price per ton sold decreased to $14.50 during the three months ended June 30, 2020, as compared to $16.06 during the same period in 2019. Timber gross margin increased during the three months ended June 30, 2020, to 90.0% as compared to 71.4% during the same period in 2019, primarily due to increased volume and changes in product mix. The cost of timber revenue is primarily fixed, which also resulted in an increase to gross margin for the period.
Other operating expenses include salaries and benefits, property taxes, CDD assessments, professional fees, marketing, project administration and other administrative expenses.
The increase of $0.5 million in depreciation, amortization and depletion expense during the three months ended June 30, 2020, as compared to the same period in 2019, was primarily due to new properties placed in service.
Interest expense primarily includes interest incurred from our commercial leasing project financing and CDD debt.
Six months ended June 30, 2020 compared to the six months ended June 30, 2019
Total leasing revenue increased $2.0 million, or 28.2%, during the six months ended June 30, 2020, as compared to the same period in 2019. This increase is primarily due to new leases at Pier Park Crossings apartments, which began leasing in the second quarter of 2019, as well as higher rental rates. Cost of leasing revenue during the six months ended June 30, 2020 includes $0.7 million of business interruption insurance proceeds received for Pier Park Crossings apartments related to Hurricane Michael. Leasing gross margin increased during the six months ended June 30, 2020 to 79.1%, as compared to 70.4% during the same period in 2019. Excluding the business interruption proceeds received during the six months ended June 30, 2020, our leasing gross margin was 71.4% during the six months ended June 30, 2020, as compared to 70.4% during the same period in 2019. As of June 30, 2020, we had net rentable square feet of approximately 898,000, of which approximately 758,000 square feet was under lease. As of June 30, 2019, we had net rentable square feet of approximately 823,000, of which approximately 758,000 square feet was under lease. During the six months ended June 30, 2020 we provided tenant rent abatements totaling $0.1 million, along with lease deferrals of $0.3 million due to the impact of the COVID-19 pandemic.
The diversity of our commercial segment complements the growth of our communities and our residential and hospitality segments. Commercial and rural real estate revenue can vary depending on the proximity to developed areas and the mix and characteristics of commercial and rural real estate sold in each period, with varying compositions of retail, office, industrial and other commercial uses. During the six months ended June 30, 2020, we had twelve commercial and rural real estate sales totaling approximately 201 acres for $5.1 million, resulting in a gross profit margin of approximately 72.5%. Commercial and rural real estate revenue for the six months ended June 30, 2020 included $1.8 million related to the sale of the SouthWood Town Center. During the six months ended June 30, 2019, we had nine commercial and rural real estate sales totaling approximately 106 acres for $2.4 million, resulting in a gross profit margin of approximately 95.8%. As our focus continues to evolve more towards recurring revenue from leasing operations, we expect to have limited commercial and rural real estate sales. Further, we may transform and operate leasing properties for higher and better use. This may result in certain assets moving from the commercial segment to the hospitality segment.
Timber revenue increased by $2.6 million during the six months ended June 30, 2020, as compared to the same period in 2019. The increase is primarily due to an increase in the amount of tons sold, along with price increases and product mix changes. The revenue for the six months ended June 30, 2019, was affected by Hurricane Michael’s significant market impact after landfall in October 2018. There were 191,000 tons sold during the six months ended June 30, 2020, as compared to 61,000 tons sold during the same period in 2019. The average price per ton sold increased