Where can I find the records of the 27th, 13th and 10th infantries from 1907-1913?  My grandfather was in these units, but because there was no war, I can't find where he went?

Linda Blanchard You'll need to request a number of record series to compile data on his service.

You can look in the NARA catalog catalog.archives.gov using the following numbers to locate data on different record sets.  Then you can visit a NARA facility to view them yourself, hire a researcher to locate and copy for you, or pay the NARA copy services for a copy.  Personal records are as follows...

NARA ID 300390 (Enlistment Papers, United States Army, July 15, 1894 - Oct. 31, 1912), these are filed by surname.

NARA ID 654713 (Personal Papers, 1812-1912), these are filed by unit (27th Inf, 13th Inf, 10th Inf) and then by surname.  This may have clinical data.

NARA ID 655639 (Carded Medical Records, Regular Army, 1894-1912), these are filed by unit (27th Inf, 13th Inf, 10th Inf) and then by surname.  This may have health and clinical data.

NARA ID 655603 (Record Of The Examination Of Recruits For The Regular Army, 1884-1912), these are filed by surname.  Good source of personal data.

Researching unit records is slightly more complicated.  There are some returns and reports on microfilm and subsequently digitized by Ancestry.com.  You can look there for Returns of Regular Army Infantry units on microfilm pub M665, and online at ancestry.  You can see where the unit was stationed, where and when they traveled, engaged in battle or other labors, and who came and went during the month (enlisted, discharged, or died).

Here is an example of a record of McFarland being discharged from 27th Reg't US Inf, as recorded on a return found on ancestry.com :

If you can get to the NARA facility in Washington, DC or have someone look for you, you may also wish to initiate a  search in Record Group 391 : Records of US Army Mobile Commands... basically the records of the Army's infantry, artillery and cavalry units from the mid-19th century through 1916-ish, (with some exceptions and gaps).  There should be records for each unit McFarland served in, as well as some indications of where else you may wish to search.  These records have not been digitized.

If he went overseas, you may wish to expand your search to Record Group 395 (Overseas Commands) or, if he stayed in the US, Record Group 393 (Continental Commands).  Perhaps he qualified for and applied for a medal or badge, which records could be in Record Group 92, entry 256 (alpha index to applications for medals and badges).  Perhaps he was subject to a Courts Martial, which records can be found in Record group 153 (JAG).  There are many possible sources of data on soldiers who served before WW1, all of which are at the NARA facility in Washington, DC.

I hope this helps you get started.