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tokens: comprehensive data on jet motions come from studies of the nearest sources, particularly the Fanaroff–Riley type-I (FR I; Fanaroff Riley 1974 ) radio galaxies M87 (Reid et al. 1989 ; Biretta et al. 1995 ; Cheung et al. 2007 ; Kovalev et al. 2007 ) and Centaurus A (Goodger et al. 2010 ; Müller et al. 2014 ). M87 is a nearby source, at a distance of only 16.7 Mpc (Blakeslee et al. 2009 ), that hosts a bright jet spanning 20′′, ∼1.6 kpc projected, from the central AGN of the system. Kiloparsec-scale, knotted structure has been directly observed within the jet using radio, optical, and X-ray observations (e.g., Owen et al. 1989 ; Sparks et al. 1996 ; Harris et al. 1997 ; Perlman et al. 2001 ; Marshall et al. 2002 ; Perlman Wilson 2005 ; Meyer et al. 2013 ). Previous measurements of proper motions in M87 have detected sub-relativistic speeds within a parsec of the AGN using the Very Long Baseline Interferometry (VLBI; Reid et al. 1989 ; Kovalev et al. 2007 ; Mertens et al. 2016 ; Walker et al. 2018 ). Superluminal motions on larger-scales were detected from the VLBI (Cheung et al. 2007 ; Giroletti et al. 2012 ), the Very Large Array (VLA; Biretta et al. 1995 ), and the Hubble Space Telescope ( HST ; Biretta et al. 1999 ; Meyer et al. 2013 ). While proper motions have yet to be detected at higher energies, measuring the kinematics of X-ray-emitting regions potentially provides the best probe for sites of particle acceleration because high energy radiation is produced by more energetic particles. Recent work from Snios et al. ( 2019 ) measured X-ray proper motions for the first time in the jet of Centaurus A, at a distance of 3.8 Mpc (Harris et al. 2010 ), by applying new methods to analyze Chandra observations. We may apply those techniques to measure proper motions in the X-ray jet of M87. In this work, we investigate proper motions and brightness variations within the X-ray jet of M87 using two Chandra observations separated by 5 yr. The remainder of the paper is structured as follows. Section 2 discusses the details of the Chandra observations and the corresponding data reduction. In Section 3 , difference maps are generated from the coaligned observations and statistical uncertainties are quantified. Evidence of proper motion for the innermost knots of the X-ray jet are presented in Section 4 . In Section 5 , the proper motion results are compared with measurements from other wavelengths. Lastly, brightness changes of the knots are utilized to investigate both the primary mechanism for fading and the magnetic field strengths of the knots. 2. Data Acquisition and Reduction The jet of M87 is known to be a bright X-ray source. In existing Chandra observations with the Advanced CCD Imaging Spectrometer (ACIS), several features of the jet, including the AGN and HST-1, are significantly affected by pile-up (>0.25 counts frame −1 ; Marshall et al. 2002 ; Wilson Yang 2002 ; Harris et al. 2003 ). ACIS observations were initially considered for our