Metaphor is replete in discourse about immigration. Recent work shows that metaphoric framing can influence attitudes toward immigration (e.g., Landau et al., 2009). However, we know little about how and when specific information in the source domain drives this effect. Our study takes a novel approach, examining how varying intensity of information in the source domain frame influences attitudes toward immigrants and immigration in the U.S. We analyze various metaphors but we focus especially on intensity effects in the conceptual metaphor IMMIGRATION IS FLUID TRANSFER. For the FLUID TRANSFER source domain, we investigate how varying intensity of flow (e.g., rate) influences attitudes about immigration, including whether immigrants should have access to social services and what type of wall should be built, if at all. Our results make a valuable contribution to metaphor research by revealing what information within the source domain has the most (or least) robust effects on reasoning.