Time Series merge with ID classification

[John Fisher]

Hello,
I am currently trying to connect time series data (with long/lat attributes for each observation) to a different dataset that contains district centroids. I want to determine which grid points lie within 100 KM of each district center. I am using geodist for this and it works fine if I limit the merge to just a single date (there are no overlapping variables so I have to use "cross"). I then only end up with data for 1/1/09 this way and also need the other 364 days. Is there an easier way to do this than my code below?

local satafiles: dir . files "*.csv"
foreach file of local satafiles {
    import delimited using `file', clear
    gen newdate = mdy(month, day, year)
    egen newid = group(newdate)
    bysort newid: gen id=_n
    save `file'.dta, replace
    keep if newid==1
    cross using griddata.dta
    geodist latitude longitude centroid_latitude centroid_longitude, gen(dist)
    merge m:m id using `file'.dta
    save `file'.dta, replace
    }

}

Any help would be very greatly appreciated and let me know if I left out any relevant information!