DEBT

As of March 31, 2019, we owned 88 apartment communities, of which 48 served as collateral for mortgage loans. The majority of these mortgage loans were non-recourse to us other than for standard carve-out obligations. As of March 31, 2019, we believe that there are no material defaults or instances of noncompliance in regards to any of these mortgages payable.

As of March 31, 2019, we owned 40 apartment communities that were not encumbered by mortgages, with 30 of those properties providing credit support for our unsecured borrowings. Our primary unsecured credit facility is a revolving, multi-bank line of credit, with the Bank of Montreal serving as administrative agent. Our line of credit has total commitments of $250.0 million, with borrowing capacity based on the value of properties contained in the unencumbered asset pool ("UAP"). As of March 31, 2019, the UAP provided for a borrowing capacity of $204.4 million, with additional borrowing availability of $85.7 million beyond the $118.7 million drawn, including the balance on our operating line of credit (discussed below). This credit facility matures on August 31, 2022, with one twelve-month option to extend the maturity date at our election.

We have unsecured term loans of $70.0 million and $75.0 million, which mature on January 15, 2024 and on August 31, 2025, respectively.

The interest rates on the line of credit and term loans are based, at our option, on either the lender's base rate plus a margin, ranging from 35-85 basis points, or the London Interbank Offered Rate ("LIBOR"), plus a margin that ranges from 135-190 basis points based on our consolidated leverage. Our line of credit and term loans are subject to customary financial covenants and limitations. We believe that we are in compliance with all such financial covenants and limitations as of March 31, 2019.

We also have a $6.0 million operating line of credit. This operating line of credit is designated to enhance treasury management activities and more effectively manage cash balances. This operating line has a one-year term, with pricing based on a market spread plus the one-month LIBOR index rate. As of March 31, 2019, we had $4.5 million outstanding on this operating line compared to no outstanding balance as of December 31, 2018.

The following table summarizes our indebtedness at March 31, 2019:



	(in thousands)
	March 31, 2019			December 31, 2018			Weighted Average Maturity in Years at March 31, 2019
Unsecured lines of credit⁽¹⁾	$	103,677		$	57,500		3.3
Term loans	145,000			145,000			5.6
Unsecured debt	248,677			202,500
Secured line of credit⁽¹⁾	15,000			—			3.4
Mortgages payable - fixed	432,587			445,974			4.2
Total debt	$	696,264		$	648,474		4.3
Weighted average interest rate on primary line of credit	3.90		%	3.72		%
Weighted average interest rate on operating line of credit	4.40		%	—
Weighted average interest rate on term loans (rate with swap)	3.99		%	4.01		%
Weighted average interest rate on mortgages payable	4.54		%	4.58		%


(1)	Our revolving line of credit consists primarily of unsecured borrowings. A portion of the line was secured in connection with our acquisition of SouthFork Townhomes, under an agreement that allowed us to offer the seller tax protection upon purchase.

The aggregate amount of required future principal payments on mortgages payable and term loans as of March 31, 2019, was as follows:



	(in thousands)
2019 (remainder)	$	25,926
2020	76,873
2021	104,547
2022	40,917
2023	48,546
Thereafter	280,778
Total payments	$	577,587