proximity matrix where elements are coded unity if the distance between states is less than
340.50 miles.2
Table 1 shows the average productivity level across the lower 48 states and the
District of Columbia in each of the sectors, including the sectoral total, as well as the
coefficient of variation expressed as a percentage. The mining sector is the most variable in
term of productivity with coefficients of variation of 60% and 50% in 1963 and 1997,
respectively. The Finance Insurance and Real Estate sector (hereafter FIRE) is by far the
most productive sector with productivity levels of $128,474 in 1963, and $193,468 in 1997.
The mining sector comes in second after FIRE in both years, respectively. While the
variation in productivity level has decreased sharply for the mining sector between 1963 and
1997, and slightly for the government sector, it has increased for the other sectors with
manufacturing showing the largest increase.
[Table 1 about here]
Table 2 shows the employment and output shares across sectors for the years 1963
and 1997. Comparing both years, the output share has increased in the FIRE and Services
sectors, while it has declined in all other sectors. The same pattern is apparent for the
employment share data.
[Table 2 about here]
2 The distance of 340.50 miles represents the minimum cutoff distance required to ensure that each state is
linked to at least one other state.