Delorme Pages Tutorial
Detailed instructions on the method for drawing grid lines onto the Pennsylvania DeLorme Atlas & Gazetteer for marking the boundaries of the individual survey blocks for the 2nd Pennsylvania Breeding Bird Atlas, in order to assist people in identifying blocks for which they may want to volunteer.

Briefly, as many of you already know, the state is divided into 57 regions for the bird atlas, and these regions are based directly on the pagination of the DeLorme Atlas: 46 of the regions are the Pennsylvania portion of exactly one page of the DeLorme Atlas; 11 regions are derived from 2-3 adjacent pages of the DeLorme Atlas (these conjoined regions are 26/28, 27/29, 54/55, 67/68, 82/83, 84/85, 86/87, 88/89, 90/91, 92/93, 94/95/96). The average number of blocks per region is 87, and the vast majority (44 regions) contain exactly 84 breeding bird atlas blocks. On two facing pages of the DeLorme Atlas, there are exactly 28 USGS 7.5-minute series topo quad map equivalents. There are six equal-sized breeding bird atlas blocks per quadrangle map, giving 168 atlas blocks per two DeLorme pages. To draw the outlines of these blocks, carefully do the following:

Start by making marks at every seven and a half grid marks along the sides, top, and bottom of two facing DeLorme pages. Draw the grid connecting these marks (look also for the three very thin crosshairs that your lines should intersect from top-to-bottom and side-to-side across each page of the map itself), and you will have 28 rectangles (these are the 7.5-min. topo quads outlines). Notice that the alphanumeric coordinates along the top (1-7) and sides (A-D) of the DeLorme pages correspond to the topo quadrangles you have outlined. You will notice, too, that one column (column 4) of the topo quads is split evenly between the two facing DeLorme map pages.

To get at the Atlas blocks themselves, you will have to divide each of the 28 topo quads exactly in half (3.75-minute sections) vertically and into equal 2.5-minute thirds horizontally. Once this is done, you will have 168 blocks, each of which is about 1 1/4 inch on each side. Every block is contained within one of the 28 topo quads, and all can easily be identified in the following way (for example, if you want to contact a Regional Coordinator about helping in the block in which your house or favorite birding spot is located): The first part of each Block I.D. is the page number of the DeLorme Atlas containing the block, followed by the coordinates (letter first, number second) identifying the topo quad, and, finally, the breeding bird atlas block number within the topo quad (numbered 1-6 from upper left to bottom right). If you wanted to be an Atlas volunteer for the block containing the town of Franklin in Venango County, you would contact the Region 43 coordinator and request block 43A75, because Franklin is on page 43, in the topo quad designated by the coordinates A7, and in block 5 (the southwestern block) of that topo quad. All 4,937 blocks in the breeding bird atlas are uniquely and easily identified in this way.