Nitrogen dioxide column abundances were measured during the Texas Air Quality Study 2000 using visible absorption spectroscopy from aircraft. The method allows for quantification of the total number of nitrogen dioxide molecules in the troposphere and is hence a useful tool for measuring the burden of this key trace gas. In particular, we focus here on observations carried out in and around Houston, including focussed flights to measure the fluxes of nitrogen dioxide emitted from power plants. This remote sensing technique can be used to infer fluxes irrespective of the aircraft altitude, the height or uniformity of the boundary layer, etc. We will show that our nitrogen dioxide measurements agree very well with in-situ nitrogen dioxide measurements, and that both compare well with reported emissions from the key point sources. Thus, remote sensing of nitrogen dioxide complements in-situ methods and allows for a more comprehensive understanding of point source emissions.