Drawing on government data on the American workforce, labor economists highlight several patterns in the low-wage workforce:

• Most workers don’t work the minimum wage for very long. Of workers who are 10 years into their careers, only about 13 percent have spent half or more of their career earning within $1.50 of the minimum wage, according to a 2001 study.
• Minimum-wage workers are concentrated in low-skill service-sector occupations, including food service, retail, and motel housekeeping. Among Labor Department occupations, “leisure/ hospitality” leads the pack with 14.3 percent of workers earning $5.15 or less per hour. (Workers in some occupations such as food service can earn less than $5.15 if they earn enough tips to equal the minimum.) By contrast, just 0.4 percent of manufacturing workers earn minimum wage.
• Of the 6.6 million workers who would be directly affected by the proposed minimum-wage hike to $7.25 an hour, 61 percent are female, 29 percent are age 16 to 19, 21 percent are Hispanic, 16 percent are black, and 9 percent are single parents, according to the Economic Policy Institute.

  Those numbers are all higher than the share of those groups in the total workforce. By contrast, 16 percent of those affected will be married parents – many fewer than the 29 percent of all workers who are in that group.

• Many low-wage workers also face a high level of job insecurity. People with low skills are more likely to be unemployed, according to government data. And many low-wage workers have only part-time jobs. Of those directly affected by the proposed wage hike, 21 percent work fewer than 20 hours per week, whereas just 5 percent of the overall workforce is in that category. In addition to low skills, barriers to employment can include substance abuse or mental illness and other disabilities.

Source: The Christian Science Monitor | Daily Online Newspaper

Some additional barriers I have noticed in Habitat families trying to get and keep a job are:

• Credit card debt
• Illness/Short term disability
• Transportation issues
• Amount of time needed for training to get a better paying job 
• Children with special needs
• Family members moving in