Presented are the main design features and performance results of the Cathode Strip Chambers for the CMS Endcap Muon system. Although the strips are unusually wide (up to 16 mm ) for the cathode-to-anode wire distance of 5 mm , the six-plane structure of these chambers yields a spatial resolution of about 80 μm , essentially uniform and independent of the strip width. In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300 ns) is obtained using a simple network of comparators. Time resolution achieved at the trigger level is ∼4 ns (rms) that allows unambiguous tagging of bunch crossings which occur every 25 ns . Aging test results, including those obtained with a recirculating gas system, are discussed; only minor aging affects were observed. The aging studies were performed with large-scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C/ cm of the total accumulated charge.