Express documents are always fun… because they can come with revenues paying two different taxes, only the first of which is an express tax. The later documents are taxed as ordinary receipts.

But both taxes were only in effect for relatively short periods, the Express tax from October 1, 1862 to March 31, 1863, and Receipt tax from August 1, 1864 to March 31, 1865.

From Mike Mahler:

You know the express companies lobbied to have the original Express stamp tax rescinded, and succeeded via the Act of March 3, 1863. But with the imposition of the Receipt tax, effective Aug 1, 1864, which included receipts for delivery of property, their receipts were again subject to that inconvenient stamp tax, this time at a flat 2c.

For the first few months [of the second period] it’s not uncommon to see them using Express stamps, even imperfs or part perfs, evidently left over after the abrupt rescinding of the earlier tax. See my book pp. 230ff. Again the companies applied pressure, and after nine months, by the Act of April 1, 1865, the tax on receipts for delivery of property by an express company was rescinded. So this makes a nice nine month period in which to search for these “Second Period” stamp taxes on express.

Express EMUs (early matching usages) were effectively only possible for an even shorter period, as the “Express” revenues were generally not available until December, 1862. So December 1862 through March 1863 is the window for Express EMUs.