American Political Science Review Vol.96,No.3 invested in manufacturing industries ends in 1919.Us- in which farming outweighed manufacturing interests ing total manufacturing production in each state is one and exporting industries were far larger than import- possible approach,but this does not permit distinctions competing concerns.My main concern here is not to between the amounts of capital and labor engaged in muddy the water when comparing the performance of production.Instead I used profits earned by capi- the class and group-based models by inadvertently in- tal in manufacturing (measured as value-added minus cluding class effects in the group-based model,or vice wage payments)as a fraction of the state income,on versa. the assumption that these profits vary from state to I have divided the main analysis into five parts,pool- state largely as a function of the total magnitude of ing the votes taken in five historical periods:1824-60 investments.28 To measure the industry characteristics 1875-1913,1922-37,194562,and1970-94.The aim is of each state I examined the size of the leading export- simply to provide some clear comparisons over time.31 ing and import-competing industries in each state using The estimations of each model have also been per- data on trade from the Department of Commerce and formed on a bill-by-bill basis and the conclusions are census data on production in manufacturing,mining. substantively identical to those reported below.32 The and agricultural sectors.For each state I calculated to- class and industry models are estimated separately,and tal production in the 10 leading exporting and import- their performance in different periods is then compared competing industries in each year as a proportion of and evaluated using Davidson and MacKinnon's(1981) the state income.29 “test.33 The analysis includes dummy variables for each bill, The"class model"includes the three indicators of the to account for individual characteristics of particu- importance of different factor classes in each state:the lar bills(or years)when examining votes in favor of value of agricultural production,employment in manu- protection.30 On the other hand,I have not included facturing,and profits earned by capital in manufactur- controls for the party affiliations and regional loca- ing.According to the basic class-based approach,we tions of members of Congress,even though previous should expect that the value of farm production is neg- work indicates that both types of variables have been atively related to votes for protection over the entire good predictors of voting patterns on trade at differ- time span,since the U.S.economy has been relatively ent times.I exclude them here to provide the clearest well endowed with land,compared to other nations,and imaginable test between the class and the industry- owners of land should thus have favored freer trade (in group models.Party affiliations and regional locations accord with the Stolper-Samuelson model).34 Owners are both strongly correlated with the measures of the of labor,on the other hand,should have favored pro- class and industry characteristics of states at different tection,since the economy has been relatively poorly levels in different periods.This in unsurprising:The endowed with labor compared with its trading partners. competing parties have appealed to very different class- and thus employment in manufacturing in states should based constituencies over the years and to supporters in be positively related to votes for protection.And,fi- different geographical regions,and those regions them- nally,according to Rogowski (1989,29),the United selves have often displayed marked differences in their States is properly regarded as a capital-scarce economy economic composition in terms of both factor classes for most of the period prior to 1914,transforming into and trade-affected industries (see Kim 1998).In the a capital-abundant economy sometime before the First antebellum years,for instance,the Jackson Democrats World War.We should thus expect a change in the pol- in Congress were elected mainly from Southern states icy preferences of owners of capital sometime between the second and the third periods examined here (or perhaps even earlier),with a shift away from support 28 The measure is strongly correlated(at 0.92)with the total capi- for protection.In terms of the estimated effects,that tal invested as a fraction of the state income for the period (1840 means that total profits earned by capital in each state 1919)for which data on the latter are available.I have performed the analysis using a range of alternative measures of the class variables, including the total value of land in agriculture and total land area(for farmers),aggregate wages in manufacturing (for labor),and total 31 The division of the post-1945 period just recognizes that U.S.trade manufacturing production and production per worker(for capital). patterns were quite volatile in the immediate postwar period,as the The key results,discussed in the next section,are substantively iden- European and Japanese economies were rebuilding,and(not coin- tical regardless of which combination of measures is employed. cidentally)the two political parties switched sides on the trade issue 29 The 10 leading exporting and import-competing industries in each in the 1960s. year in which a vote occurred were identified using figures for exports and imports drawn from the U.S.Department of Commerce's Com- 32 Note that since some members of Congress vote on more than one bill in each of the pools considered,all observations are not merce and Navigation of the United States.This approach follows that independent and so the estimated standard errors are biased in a used by Gilligan (1997),though the set of votes/years differs in that downward direction in that analysis.I am grateful to an anonymous my analysis includes the antebellum period as well as many bills after reviewer for making this point.Results for the bill-by-bill analysis 1870 that have been excluded from previous studies.The full lists if the top 10 export and import-competing industries in each year are eo iry variables are colimearinand available from the author. 30 I have also examined specifications of each model that include degrees that differ over time,so including them all in one estima- tion would actually make it very difficult to interpret the size and variables such as dummies for bills with provisions delegating author- ity to the president to negotiate tariff reductions with other nations ee on US factor e and for bills that ratified trade treaties already negotiated.The key dowments,with deductions about class preferences on trade derived substantive results are identical to the ones reported below so the from the Stolper-Samuelson theorem.Rogowski's designations are simplest specifications have been presented. applied here. 599American Political Science Review invested in manufacturing industries ends in 1919. Us￾ing total manufacturing production in each state is one possible approach, but this does not permit distinctions between the amounts of capital and labor engaged in production. Instead I used profits earned by capi￾tal in manufacturing (measured as value-added minus wage payments) as a fraction of the state income, on the assumption that these profits vary from state to state largely as a function of the total magnitude of investment^.^^ To measure the industry characteristics of each state I examined the size of the leading export￾ing and import-competing industries in each state using data on trade from the Department of Commerce and census data on production in manufacturing, mining, and agricultural sectors. For each state I calculated to￾tal production in the 10 leading exporting and import￾competing industries in each year as a proportion of the state income.29 The analysis includes dummy variables for each bill, to account for individual characteristics of particu￾lar bills (or years) when examining votes in favor of prote~tion.~~ On the other hand, I have not included controls for the party affiliations and regional loca￾tions of members of Congress, even though previous work indicates that both types of variables have been good predictors of voting patterns on trade at differ￾ent times. I exclude them here to provide the clearest imaginable test between the class and the industry￾group models. Party affiliations and regional locations are both strongly correlated with the measures of the class and industry characteristics of states at different levels in different periods. This in unsurprising: The competing parties have appealed to very different class￾based constituencies over the years and to supporters in different geographical regions, and those regions them￾selves have often displayed marked differences in their economic composition in terms of both factor classes and trade-affected industries (see Kim 1998). In the antebellum years, for instance, the Jackson Democrats in Congress were elected mainly from Southern states 28 The measure is strongly correlated (at 0.92) with the total capi￾tal invested as a fraction of the state income for the period (184CL 1919) for which data on the latter are available. I have performed the analysis using a range of alternative measures of the class variables, including the total value of land in agriculture and total land area (for farmers), aggregate wages in manufacturing (for labor), and total manufacturing production and production per worker (for capital). The key results, discussed in the next section, are substantively iden￾tical regardless of which combination of measures is employed. 29 The 10 leading exporting and import-competing industries in each year in which a vote occurred were identified using figures for exports and imports drawn from the U.S. Department of Commerce's Com￾merce and Navigation of the United States. This approach follows that used by Gilligan (1997), though the set of voteslyears differs in that my analysis includes the antebellum period as well as many bills after 1870 that have been excluded from previous studies. The full lists if the top 10 export and import-competing industries in each year are available from the author. 30 I have also examined specifications of each model that include variables such as dummies for bills with provisions delegating author￾ity to the president to negotiate tariff reductions with other nations and for bills that ratified trade treaties already negotiated. The key substantive results are identical to the ones reported below so the simplest specifications have been presented. Vol. 96, No. 3 in which farming outweighed manufacturing interests and exporting industries were far larger than import￾competing concerns. My main concern here is not to muddy the water when comparing the performance of the class and group-based models by inadvertently in￾cluding class effects in the group-based model, or vice versa. I have divided the main analysis into five parts, pool￾ing the votes taken in five historical periods: 1824-60, 1875-1913,1922-37,1945-62, and 1970-94. The aim is simply to provide some clear comparisons over time.31 The estimations of each model have also been per￾formed on a bill-by-bill basis and the conclusions are substantively identical to those reported below.32 The class and industry models are estimated separately, and their performance in different periods is then compared and evaluated using Davidson and MacKinnon's (1981) "J test."33 The "class model" includes the three indicators of the importance of different factor classes in each state: the value of agricultural production, employment in manu￾facturing, and profits earned by capital in manufactur￾ing. According to the basic class-based approach, we should expect that the value of farm production is neg￾atively related to votes for protection over the entire time span, since the U.S. economy has been relatively well endowed with land, compared to other nations, and owners of land should thus have favored freer trade (in accord with the Stolper-Samuelson Owners of labor, on the other hand, should have favored pro￾tection, since the economy has been relatively poorly endowed with labor compared with its trading partners, and thus employment in manufacturing in states should be positively related to votes for protection. And, fi￾nally, according to Rogowski (1989, 29), the United States is properly regarded as a capital-scarce economy for most of the period prior to 1914, transforming into a capital-abundant economy sometime before the First World War. We should thus expect a change in the pol￾icy preferences of owners of capital sometime between the second and the third periods examined here (or perhaps even earlier), with a shift away from support for protection. In terms of the estimated effects, that means that total profits earned by capital in each state 31 The division of the post-1945 period just recognizes that U.S. trade patterns were quite volatile in the immediate postwar period, as the European and Japanese economies were rebuilding, and (not coin￾cidentally) the two political parties switched sides on the trade issue in the 1960s. 32 Note that since some members of Congress vote on more than one bill in each of the pools considered, all observations are not independent and so the estimated standard errors are biased in a downward direction in that analysis. I am grateful to an anonymous reviewer for making this point. Results for the bill-by-bill analysis are available from the author. 33 The various class and industry variables are collinear in ways and degrees that differ over time, so including them all in one estima￾tion would actually make it very difficult to interpret the size and significance of their competing effects on voting. 34 See Rogowski (1989) for quantitative evidence on U.S. factor en￾dowments, with deductions about class preferences on trade derived from the Stolper-Samuelson theorem. Rogowski's designations are applied here