Results of the fourth annual inventory estimate that 89 percent, or 17.5 million acres, of Maine's land base (exclusive of water) is forested, making Maine the most forested state in the Nation. Over 75 percent of Maine’s forest land is dominated by the maple/beech/birch and spruce/fir forest-type groups. The volume of sawtimber on timberland has risen 75 percent since 1959 while average annual net growth (merchantable bole volume) of growing stock on timberland averaged 713 million cubic feet per year from 2013 to 2018. The density of carbon in Maine’s forest land was estimated at 88 tons per acre with soil organic carbon and live trees accounting for 87 percent of total forest carbon stocks. This summary includes additional information on forest attributes, land-use change, timber products, ownership, and forest health, among other critical forest ecosystem services. A detailed interactive report is available at https://doi.org/10.2737/NRS-RB-126-INT, and supplemental information, including (1) tables summarizing quality assurance, (2) a core set of tabular estimates for forest resources, and (3) user and database guides for P2 and P2+ protocols, can be accessed at https://doi.org/10.2737/NRS-RB-126.