10.48349/ASU/2J9R9HStrickland, JamesJamesStricklandArizona State UniversityASU Library Research Data Repository2020LawSocial SciencesLobbying; interest groups; government growth; state politics; public choiceStrickland, JamesJamesStricklandArizona State University2020-11-012020-11-23doi:10.7910/DVN/QSSIHL1563123899253882792application/pdftext/tab-separated-valuestext/tab-separated-valuestext/tab-separated-values1.0CC0 1.0What explains contemporary numbers of interest groups in America? To answer this question and help address conflicting narratives in research, I examine the rise of interest groups in the states. Assembling an original data set based on archival and secondary sources, I find that relatively few groups lobbied legislators prior to the 1960s or 1970s. During those decades, numbers of interest groups began to grow rapidly. I find that increases in lawmaking activities present inconsistent effects on the political mobilization of groups but increases in spending are strongly correlated with mobilization. In additional tests, I find that the effects of spending on group numbers vary by state and are not discernible in most states. In general, a historic transformation of state governments helps to account for the growth of state lobbying. Interest groups have remained active in state capitols ever since.