We investigate the spatial correlation properties of the solar wind in the ecliptic at 1 AU using simultaneous in situ observations by the Advanced Composition Explorer and Wind spacecraft. We present the first direct study of the spatial correlation length scale λ of fluctuations in the solar wind ion density ρ, and find it to be smaller than that of the magnetic field. We find that there is the same statistically significant increase in λ by a factor 2 from solar minimum to solar maximum for both density and magnetic field magnitude, in contrast to the components of the field, whose λ shows no discernible solar cycle variation. This is suggestive of long-range correlation in ρ and |B| which is of direct coronal origin, in contrast to that found in the B components, which is more strongly dominated by in situ evolving turbulence. The distinct correlation lengths of the density and magnetic field, and their solar cycle variation, thus provide new quantitative insights into coronal processes and their mapping out into the solar wind. These results also provide quantitative input for models of cosmic ray propagation within the heliosphere.