The heavy winter snows and the network of waterways were used to move logs to the mills. Loggers were able to drag cut trees over the winter snow to the roads or water bodies. In the southwest, the sledding season lasted about 100 days per year; the season was even longer to the north and the east. The country's network of lakes and rivers facilitated log floating, a cheap and rapid means of transport. Each spring, crews floated the logs downstream to collection points; tugs towed log bundles down rivers and across lakes to processing centers. The waterway system covered much of the country, and by the 1980s Finland had extended roadways and railroads to areas not served by waterways, effectively opening up all of the country's forest reserves to commercial use.