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The kinematic Sunyaev-Zel'dovich (kSZ) effect -- the Doppler boosting ofcosmic microwave background (CMB) photons scattering off free electrons withnon-zero line-of-sight velocity -- is an excellent probe of the distribution ofbaryons in the Universe. In this paper, we measure the kSZ effect due toionized gas traced by infrared-selected galaxies from the \emph{unWISE}catalog. We employ the "projected-field" kSZ estimator, which does not requirespectroscopic galaxy redshifts. To suppress non-kSZ foreground signalsassociated with the galaxies (e.g., dust emission and thermal SZ), thisestimator requires cleaned CMB maps, which we obtain from \emph{Planck} and\emph{WMAP} data. Using a new "asymmetric" estimator that combines differentforeground-cleaned CMB maps to maximize the signal-to-noise, we measure thekSZ$^2$-galaxy cross-power spectrum for three subsamples of the \emph{unWISE}galaxy catalog, which peak at mean redshifts $z \approx$ 0.6, 1.1, and 1.5,have average halo mass $\sim 1$-$5\times 10^{13}$ $h^{-1} M_{\odot}$, and intotal contain over 500 million galaxies. After marginalizing over CMB lensingcontributions, we measure the amplitude of the kSZ signal $A_{\rm kSZ^2} = 0.42\pm 0.31(stat.) \pm 0.14(sys.)$, $5.02 \pm 1.01(stat.) \pm 0.47(sys.)$, and$8.23 \pm 3.23(stat.) \pm 1.60(sys.)$, for the three subsamples, where $A_{\rmkSZ^2} = 1$ corresponds to our fiducial model. The combined kSZ detection S/N$>$ 5. We discuss possible explanations for the excess kSZ signal associatedwith the $z \approx 1.1$ sample, and show that foreground contamination in theCMB maps is very unlikely to be the cause. Our measurements illustrate clearlythat no baryons are missing on large scales at low redshifts.

Constraining the Baryon Abundance with the Kinematic Sunyaev-Zel'dovich Effect: Projected-Field Detection Using Planck, WMAP, and unWISE