In the years just prior to the Civil War, the economy of the North was industrializing. It was not as industrialized as it would later be, but it was much more industrial than it had been before 1830. This had a great impact on the labor system of the region.
The factories of the North employed wage laborers. Many of the workers were women and even children. Wages were generally low and working conditions were typically quite poor. Many of the workers in the factories were taken from the large pool of immigrants who came to the US, particularly in the 1840s. This system of poorly paid wage labor also applied to industries such as the mining industry.
Of course, there were still many small farmers in the North. These were people who worked for themselves, growing what they needed as well as some amount of surplus to sell. On farms like this, women and children worked as well with women caring for animals, making cloth and butter and cheese, and often raising vegetables while children did whatever they could. We do not usually talk about these farmers because the major trend in this period was towards more industrialization. However, especially early on, these small "yeoman farmers" made up a large percentage of the labor force.