The Productivity of U.S. States Since 1880

This study identifies the determinants of interstate variation in labor productivity levels at twenty-year intervals between 1880 and 1980. Focusing on fundamental rather than proximate influences, we find that institutional characteristics, physical geography, and resource abundance can account for a high proportion of the differences in state productivity levels. States with navigable waterways, a large minerals endowment, and no slaves in 1860, on average, had higher labor productivity levels throughout the sample period. No consistent support was found for two other influences given prominence in cross-country analyses of differences in incomes or productivity levels: climate and the quality of government.economic growth, productivity levels, slavery, natural resources

The Productivity of U.S. States Since 1880

This study uses state-level variation in labor productivity levels at twenty-year intervals between 1880 and 1980 to examine the relative importance of institutional and geographical influences in explaining observed and persistent differences in standards of living over time and across regions. Focusing on fundamental rather than proximate influences, we find that both institutional characteristics and some physical geography characteristics account for a high proportion of the differences in state productivity levels: states with navigable waterways, a large minerals endowment, and no slaves in 1860, on average, had higher labor productivity levels throughout the sample period. However, we find little support for two other influences that have previously received attention climate and latitude.

Multi-rate, real time image compression for images dominated by point sources

An image compression system recently developed for compression of digital images dominated by point sources is presented. Encoding consists of minimum-mean removal, vector quantization, adaptive threshold truncation, and modified Huffman encoding. Simulations are presented showing that the peaks corresponding to point sources can be transmitted losslessly for low signal-to-noise ratios (SNR) and high point source densities while maintaining a reduced output bit rate. Encoding and decoding hardware has been built and tested which processes 552,960 12-bit pixels per second at compression rates of 10:1 and 4:1. Simulation results are presented for the 10:1 case only