Most RTW states adopted RTW laws during late 1940s and 1950s. Today such laws are in effect in twenty-two states, most of them in the West and Southeast. The Northeast is the only region without a RTW state while the South (at 12) has the greatest concentration. Table 1 gives the geographic breakdown of RTW states.

The rosters of RTW and non-RTW states have changed little in a half century. After 19 states passed RTW legislation shortly after Taft-Hartley in 1947, only three non-RTW states enacted a RTW law from 1964 until 2001. Oklahoma's passage of a new law in 2001, however, shows that RTW legislation isn't entirely dormant. Only one RTW state, Indiana, has repealed its law, in 1965.

State union membership rates are strongly correlated with RTW status. According to the U.S. Bureau of Labor Statistics, all states in the Great Lakes, Mid-Atlantic and Pacific regions (i.e., non-RTW regions) had union membership rates above the national average of 13.5 percent in 2001, while all states in the East South Central and West South Central divisions had below-average rates. Overall, 29 states had union membership rates below the U.S. average, while 21 states and the District of Columbia had higher rates.

Four states had union membership rates over 20 percent in 2001-New York, Hawaii, Alaska, and Michigan (in order of decreasing share). Two states, North and South Carolina, had membership rates below 5 percent. As of 2001, half of the nation's 16.3 million union members lived in six states-California, New York, Illinois, Michigan, Ohio, and Pennsylvania. These six states accounted for 35 percent of wage and salary employment nationally.

Workers in the public sector continued to have unionization rates that were about four-times higher than their counterparts in private industry. In 2001, the unionization rate of government workers was 37.4 percent, compared with 9 percent among private sector employees (see Chart 1). Local government, which includes many workers in the heavily unionized fields of public education (the NEA is the largest union in the country), firefighting and law enforcement, had the highest unionization rate, at 43.1 percent. The construction and manufacturing industries also had higher-than-average unionization rates, at 18.4 percent and 14.6 percent, respectively. The nonagricultural industry with the lowest unionization rate in 2001 was finance, insurance, and real estate at 2.1 percent.1