We examine how legislative representation and issue activism change as parties polarize on an issue by examining immigration politics in the U.S. House. Using an original data set of the policy positions in immigration bills from 1983 to 2014, an original coding of email newsletters from 2010 to 2020, and existing speech data, we show that increased partisan disagreement on immigration and the sorting of immigrants into the Democratic Party changed the way lawmakers represent their districts on that issue. Larger foreign-born populations consistently have representatives who take pro-immigration positions, but the effect has changed from a direct effect to one mediated by partisanship. Issue attention also became asymmetrical, with Democratic lawmakers who represent more immigrants being more active on immigration policy, but no such relationship for Republicans. This suggests that for Democrats, immigration is a distributive issue driven by geographically concentrated "policy demanders" but for Republicans, it is a partisan issue that is less connected to geography. These findings have implications for who and where new policy proposals come from. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)1983(sic)(sic)2014(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),2010(sic)(sic)2020(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic), "(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)"(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)"(sic)(sic)(sic)(sic)(sic)(sic)(sic)"(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)"(sic)(sic)(sic)(sic)(sic)"(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).. Analizamos c & oacute;mo cambian la representaci & oacute;n legislativa y el activismo en torno a un tema a medida que los partidos se polarizan en torno a un stema, examinando la pol & iacute;tica de inmigraci & oacute;n en la C & aacute;mara de Representantes de Estados Unidos. Utilizando un conjunto de datos original de las posiciones pol & iacute;ticas en los proyectos de ley de inmigraci & oacute;n de 1983 a 2014, una codificaci & oacute;n original de boletines informativos por correo electr & oacute;nico de 2010 a 2020 y datos de discurso existentes, demostramos que el aumento del desacuerdo partidista sobre la inmigraci & oacute;n y la clasificaci & oacute;n de los inmigrantes en el Partido Dem & oacute;crata cambiaron la forma en que los legisladores representan a sus distritos en ese tema. Las poblaciones m & aacute;s grandes de nacidos en el extranjero tienen sistem & aacute;ticamente representantes que adoptan posiciones a favor de la inmigraci & oacute;n, pero el efecto ha cambiado de un efecto directo a uno mediado por el partidismo. La atenci & oacute;n a los temas tambi & eacute;n se volvi & oacute; asim & eacute;trica, ya que los legisladores dem & oacute;cratas que representan a m & aacute;s inmigrantes son m & aacute;s activos en la pol & iacute;tica de inmigraci & oacute;n, pero no existe tal relaci & oacute;n para los republicanos. Esto sugiere que, para los dem & oacute;cratas, la inmigraci & oacute;n es una cuesti & oacute;n distributiva impulsada por "demandantes de pol & iacute;ticas" concentrados geogr & aacute;ficamente, pero para los republicanos es una cuesti & oacute;n partidista que est & aacute; menos conectada con la geograf & iacute;a. Estos hallazgos tienen implicaciones para qui & eacute;nes y d & oacute;nde provienen las nuevas propuestas de pol & iacute;ticas.
