Obverse Design All lettering incused. Manufacturer's name is in very tiny letters at the top "AM.RY.S. CO. N.Y" above the slotted hole. First line "PANAMA" where the "P" and the last "A" are larger letters. Second line "10644" (the employee number). Last line "CANAL".
Reverse Design Blank.
Metal Brass Size and Shape Square 38 mm wide by 38 mm high. There is a oval hole or slot at the top.
Dates Issued They were issued in June, 1914 to replace the Isthmian Canal Commission issues when the ICC was abolished (April 1, 1914). All ICC checks had to be replaced by July 1, 1914. These square Panama Canal checks probably continued being issued until July 1918 when the photo id checks were instituted.
Issurer Panama Canal Company. This was the U.S. government entity set up by Congress to maintain and operate the canal.
Numbers Issued Pieces in collector hands include #711, #1091, #1135, #1564, #1606, #3445, #3452, #3885, #4538, #5313, #5346, #6635, #8830, #9798, #10644 and #131130.
Rarity Common. Manufacturer AM.RY.S.CO., N. Y. which was the American Railway Supply Company. Other Catalog Numbers Asociación Numismático's ID-12, Hamlin's PC-5 and Rulau's CZ 76.
Varieties Some checks may have one or two additional small holes. If the lettering and numbers are undamaged, there is no reduction in value for these holes.
Function These were employee id checks, issued to all Panama Canal Company employees. They were used in controlling access to Panama Canal facilities (such as commissaries and hotels). They probably were also used to identify each employee when they were cashing their pay certificate or paycheck. The ICC used pay certificates in combination with the metal checks, and the Panama Canal Company probably did the same until whenever pay checks became the standard.
Historical Note

The following quote is taken from an article by Eugene Hamlin, Jr. titled "CANAL ZONE BRASS CHECKS" which appeared in The Panama Collector newsletter (September, 1985 issue):

When the I.C.C. went out of existence in 1914 a new square Panama Canal metal check was issued. The Governor's circular of Jun 24, 1914 reserved the nos. from one thru 19,999 for gold employees with those higher nos. for use of silver employees. This circular also provided for certain distribution of numbers according to work performed. Although it is not known to this author when the various P.R.R. Co. metal checks came into use there is, however, a circular of January 6, 1915 entitled "Retirement of Panama Railroad Brass Checks" signed by the Auditor, Panama Canal which stated that P.R.R. checks would be retired and Panama Canal checks issued in lieu thereof. It went on to say that numbers 15001 to 20000 would be issued to or reserved for future use of Panama Railroad gold employees and nos. 80001 to 100,000 for P.R.R. silver employees. It also noted that nos. 80001 to 86000 would be for the Balboa agency and 86001 to 92000 for the use of the Colon agency. The P.R.R. checks would not be honored after January 15, 1915. Again, a fee or fine of 50 cents was to be paid for checks not turned in.

Numbers above 100,000 such as #131130 are also known. In view of the above paragraph, they were probably for the use of contractors or some other special group.

Population Count Sixteen specimens of this variety of brass check in collector hands are known to me. Recent sales include:
  • Check #3452- Offered for auction on eBay starting at of $95 for an auction ending April 19, 2007. Did not sell.
  • Check #1135- Offered for auction on eBay starting at of $95 for an auction ending April 19, 2007. Did not sell.
  • Check #131130 - Auction sale on ebay on February 9, 2007 for $56.66 plus $5.25 shipping.
  • Check #5313 - Auction sale on ebay on September 29, 2006 for $112.99 plus $3.99 shipping.
  • Check #1135 - Auction sale on ebay on January 26, 2003 for $71.00.
  • Check #10644 - Auction sale on ebay on January 20, 2001 for $76.01.

Other Examples of CK-3.1
Picture of another CK-3.1 Picture of another CK-3.1
Scale: 4 pixels equals one millimeter

Payday for Gold Roll Employees at the Administration Building 1916
Payday for Gold Roll Employees at the Administration Building 1916
From the Canal Zone Review, October 1979 Edition